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-
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-
-Network Working Group M. Crispin
-Request for Comments: 2060 University of Washington
-Obsoletes: 1730 December 1996
-Category: Standards Track
-
-
- INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1
-
-Status of this Memo
-
- This document specifies an Internet standards track protocol for the
- Internet community, and requests discussion and suggestions for
- improvements. Please refer to the current edition of the "Internet
- Official Protocol Standards" (STD 1) for the standardization state
- and status of this protocol. Distribution of this memo is unlimited.
-
-Abstract
-
- The Internet Message Access Protocol, Version 4rev1 (IMAP4rev1)
- allows a client to access and manipulate electronic mail messages on
- a server. IMAP4rev1 permits manipulation of remote message folders,
- called "mailboxes", in a way that is functionally equivalent to local
- mailboxes. IMAP4rev1 also provides the capability for an offline
- client to resynchronize with the server (see also [IMAP-DISC]).
-
- IMAP4rev1 includes operations for creating, deleting, and renaming
- mailboxes; checking for new messages; permanently removing messages;
- setting and clearing flags; [RFC-822] and [MIME-IMB] parsing;
- searching; and selective fetching of message attributes, texts, and
- portions thereof. Messages in IMAP4rev1 are accessed by the use of
- numbers. These numbers are either message sequence numbers or unique
- identifiers.
-
- IMAP4rev1 supports a single server. A mechanism for accessing
- configuration information to support multiple IMAP4rev1 servers is
- discussed in [ACAP].
-
- IMAP4rev1 does not specify a means of posting mail; this function is
- handled by a mail transfer protocol such as [SMTP].
-
- IMAP4rev1 is designed to be upwards compatible from the [IMAP2] and
- unpublished IMAP2bis protocols. In the course of the evolution of
- IMAP4rev1, some aspects in the earlier protocol have become obsolete.
- Obsolete commands, responses, and data formats which an IMAP4rev1
- implementation may encounter when used with an earlier implementation
- are described in [IMAP-OBSOLETE].
-
-
-
-
-
-Crispin Standards Track [Page 1]
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-RFC 2060 IMAP4rev1 December 1996
-
-
- Other compatibility issues with IMAP2bis, the most common variant of
- the earlier protocol, are discussed in [IMAP-COMPAT]. A full
- discussion of compatibility issues with rare (and presumed extinct)
- variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is
- primarily of historical interest.
-
-Table of Contents
-
-IMAP4rev1 Protocol Specification .................................. 4
-1. How to Read This Document ................................. 4
-1.1. Organization of This Document ............................. 4
-1.2. Conventions Used in This Document ......................... 4
-2. Protocol Overview ......................................... 5
-2.1. Link Level ................................................ 5
-2.2. Commands and Responses .................................... 6
-2.2.1. Client Protocol Sender and Server Protocol Receiver ....... 6
-2.2.2. Server Protocol Sender and Client Protocol Receiver ....... 7
-2.3. Message Attributes ........................................ 7
-2.3.1. Message Numbers ........................................... 7
-2.3.1.1. Unique Identifier (UID) Message Attribute ......... 7
-2.3.1.2. Message Sequence Number Message Attribute ......... 9
-2.3.2. Flags Message Attribute .................................... 9
-2.3.3. Internal Date Message Attribute ........................... 10
-2.3.4. [RFC-822] Size Message Attribute .......................... 11
-2.3.5. Envelope Structure Message Attribute ...................... 11
-2.3.6. Body Structure Message Attribute .......................... 11
-2.4. Message Texts ............................................. 11
-3. State and Flow Diagram .................................... 11
-3.1. Non-Authenticated State ................................... 11
-3.2. Authenticated State ....................................... 11
-3.3. Selected State ............................................ 12
-3.4. Logout State .............................................. 12
-4. Data Formats .............................................. 12
-4.1. Atom ...................................................... 13
-4.2. Number .................................................... 13
-4.3. String ..................................................... 13
-4.3.1. 8-bit and Binary Strings .................................. 13
-4.4. Parenthesized List ........................................ 14
-4.5. NIL ....................................................... 14
-5. Operational Considerations ................................ 14
-5.1. Mailbox Naming ............................................ 14
-5.1.1. Mailbox Hierarchy Naming .................................. 14
-5.1.2. Mailbox Namespace Naming Convention ....................... 14
-5.1.3. Mailbox International Naming Convention ................... 15
-5.2. Mailbox Size and Message Status Updates ................... 16
-5.3. Response when no Command in Progress ...................... 16
-5.4. Autologout Timer .......................................... 16
-5.5. Multiple Commands in Progress ............................. 17
-
-
-
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-RFC 2060 IMAP4rev1 December 1996
-
-
-6. Client Commands ........................................... 17
-6.1. Client Commands - Any State ............................... 18
-6.1.1. CAPABILITY Command ........................................ 18
-6.1.2. NOOP Command .............................................. 19
-6.1.3. LOGOUT Command ............................................ 20
-6.2. Client Commands - Non-Authenticated State ................. 20
-6.2.1. AUTHENTICATE Command ...................................... 21
-6.2.2. LOGIN Command ............................................. 22
-6.3. Client Commands - Authenticated State ..................... 22
-6.3.1. SELECT Command ............................................ 23
-6.3.2. EXAMINE Command ........................................... 24
-6.3.3. CREATE Command ............................................ 25
-6.3.4. DELETE Command ............................................ 26
-6.3.5. RENAME Command ............................................ 27
-6.3.6. SUBSCRIBE Command ......................................... 29
-6.3.7. UNSUBSCRIBE Command ....................................... 30
-6.3.8. LIST Command .............................................. 30
-6.3.9. LSUB Command .............................................. 32
-6.3.10. STATUS Command ............................................ 33
-6.3.11. APPEND Command ............................................ 34
-6.4. Client Commands - Selected State .......................... 35
-6.4.1. CHECK Command ............................................. 36
-6.4.2. CLOSE Command ............................................. 36
-6.4.3. EXPUNGE Command ........................................... 37
-6.4.4. SEARCH Command ............................................ 37
-6.4.5. FETCH Command ............................................. 41
-6.4.6. STORE Command ............................................. 45
-6.4.7. COPY Command .............................................. 46
-6.4.8. UID Command ............................................... 47
-6.5. Client Commands - Experimental/Expansion .................. 48
-6.5.1. X<atom> Command ........................................... 48
-7. Server Responses .......................................... 48
-7.1. Server Responses - Status Responses ....................... 49
-7.1.1. OK Response ............................................... 51
-7.1.2. NO Response ............................................... 51
-7.1.3. BAD Response .............................................. 52
-7.1.4. PREAUTH Response .......................................... 52
-7.1.5. BYE Response .............................................. 52
-7.2. Server Responses - Server and Mailbox Status .............. 53
-7.2.1. CAPABILITY Response ....................................... 53
-7.2.2. LIST Response .............................................. 54
-7.2.3. LSUB Response ............................................. 55
-7.2.4 STATUS Response ........................................... 55
-7.2.5. SEARCH Response ........................................... 55
-7.2.6. FLAGS Response ............................................ 56
-7.3. Server Responses - Mailbox Size ........................... 56
-7.3.1. EXISTS Response ........................................... 56
-7.3.2. RECENT Response ........................................... 57
-
-
-
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-RFC 2060 IMAP4rev1 December 1996
-
-
-7.4. Server Responses - Message Status ......................... 57
-7.4.1. EXPUNGE Response .......................................... 57
-7.4.2. FETCH Response ............................................ 58
-7.5. Server Responses - Command Continuation Request ........... 63
-8. Sample IMAP4rev1 connection ............................... 63
-9. Formal Syntax ............................................. 64
-10. Author's Note ............................................. 74
-11. Security Considerations ................................... 74
-12. Author's Address .......................................... 75
-Appendices ........................................................ 76
-A. References ................................................ 76
-B. Changes from RFC 1730 ..................................... 77
-C. Key Word Index ............................................ 79
-
-
-IMAP4rev1 Protocol Specification
-
-1. How to Read This Document
-
-1.1. Organization of This Document
-
- This document is written from the point of view of the implementor of
- an IMAP4rev1 client or server. Beyond the protocol overview in
- section 2, it is not optimized for someone trying to understand the
- operation of the protocol. The material in sections 3 through 5
- provides the general context and definitions with which IMAP4rev1
- operates.
-
- Sections 6, 7, and 9 describe the IMAP commands, responses, and
- syntax, respectively. The relationships among these are such that it
- is almost impossible to understand any of them separately. In
- particular, do not attempt to deduce command syntax from the command
- section alone; instead refer to the Formal Syntax section.
-
-1.2. Conventions Used in This Document
-
- In examples, "C:" and "S:" indicate lines sent by the client and
- server respectively.
-
- The following terms are used in this document to signify the
- requirements of this specification.
-
- 1) MUST, or the adjective REQUIRED, means that the definition is
- an absolute requirement of the specification.
-
- 2) MUST NOT that the definition is an absolute prohibition of the
- specification.
-
-
-
-
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-RFC 2060 IMAP4rev1 December 1996
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-
- 3) SHOULD means that there may exist valid reasons in particular
- circumstances to ignore a particular item, but the full
- implications MUST be understood and carefully weighed before
- choosing a different course.
-
- 4) SHOULD NOT means that there may exist valid reasons in
- particular circumstances when the particular behavior is
- acceptable or even useful, but the full implications SHOULD be
- understood and the case carefully weighed before implementing
- any behavior described with this label.
-
- 5) MAY, or the adjective OPTIONAL, means that an item is truly
- optional. One vendor may choose to include the item because a
- particular marketplace requires it or because the vendor feels
- that it enhances the product while another vendor may omit the
- same item. An implementation which does not include a
- particular option MUST be prepared to interoperate with another
- implementation which does include the option.
-
- "Can" is used instead of "may" when referring to a possible
- circumstance or situation, as opposed to an optional facility of
- the protocol.
-
- "User" is used to refer to a human user, whereas "client" refers
- to the software being run by the user.
-
- "Connection" refers to the entire sequence of client/server
- interaction from the initial establishment of the network
- connection until its termination. "Session" refers to the
- sequence of client/server interaction from the time that a mailbox
- is selected (SELECT or EXAMINE command) until the time that
- selection ends (SELECT or EXAMINE of another mailbox, CLOSE
- command, or connection termination).
-
- Characters are 7-bit US-ASCII unless otherwise specified. Other
- character sets are indicated using a "CHARSET", as described in
- [MIME-IMT] and defined in [CHARSET]. CHARSETs have important
- additional semantics in addition to defining character set; refer
- to these documents for more detail.
-
-2. Protocol Overview
-
-2.1. Link Level
-
- The IMAP4rev1 protocol assumes a reliable data stream such as
- provided by TCP. When TCP is used, an IMAP4rev1 server listens on
- port 143.
-
-
-
-
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-
-
-2.2. Commands and Responses
-
- An IMAP4rev1 connection consists of the establishment of a
- client/server network connection, an initial greeting from the
- server, and client/server interactions. These client/server
- interactions consist of a client command, server data, and a server
- completion result response.
-
- All interactions transmitted by client and server are in the form of
- lines; that is, strings that end with a CRLF. The protocol receiver
- of an IMAP4rev1 client or server is either reading a line, or is
- reading a sequence of octets with a known count followed by a line.
-
-2.2.1. Client Protocol Sender and Server Protocol Receiver
-
- The client command begins an operation. Each client command is
- prefixed with an identifier (typically a short alphanumeric string,
- e.g. A0001, A0002, etc.) called a "tag". A different tag is
- generated by the client for each command.
-
- There are two cases in which a line from the client does not
- represent a complete command. In one case, a command argument is
- quoted with an octet count (see the description of literal in String
- under Data Formats); in the other case, the command arguments require
- server feedback (see the AUTHENTICATE command). In either case, the
- server sends a command continuation request response if it is ready
- for the octets (if appropriate) and the remainder of the command.
- This response is prefixed with the token "+".
-
- Note: If, instead, the server detected an error in the command, it
- sends a BAD completion response with tag matching the command (as
- described below) to reject the command and prevent the client from
- sending any more of the command.
-
- It is also possible for the server to send a completion response
- for some other command (if multiple commands are in progress), or
- untagged data. In either case, the command continuation request
- is still pending; the client takes the appropriate action for the
- response, and reads another response from the server. In all
- cases, the client MUST send a complete command (including
- receiving all command continuation request responses and command
- continuations for the command) before initiating a new command.
-
- The protocol receiver of an IMAP4rev1 server reads a command line
- from the client, parses the command and its arguments, and transmits
- server data and a server command completion result response.
-
-
-
-
-
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-
-2.2.2. Server Protocol Sender and Client Protocol Receiver
-
- Data transmitted by the server to the client and status responses
- that do not indicate command completion are prefixed with the token
- "*", and are called untagged responses.
-
- Server data MAY be sent as a result of a client command, or MAY be
- sent unilaterally by the server. There is no syntactic difference
- between server data that resulted from a specific command and server
- data that were sent unilaterally.
-
- The server completion result response indicates the success or
- failure of the operation. It is tagged with the same tag as the
- client command which began the operation. Thus, if more than one
- command is in progress, the tag in a server completion response
- identifies the command to which the response applies. There are
- three possible server completion responses: OK (indicating success),
- NO (indicating failure), or BAD (indicating protocol error such as
- unrecognized command or command syntax error).
-
- The protocol receiver of an IMAP4rev1 client reads a response line
- from the server. It then takes action on the response based upon the
- first token of the response, which can be a tag, a "*", or a "+".
-
- A client MUST be prepared to accept any server response at all times.
- This includes server data that was not requested. Server data SHOULD
- be recorded, so that the client can reference its recorded copy
- rather than sending a command to the server to request the data. In
- the case of certain server data, the data MUST be recorded.
-
- This topic is discussed in greater detail in the Server Responses
- section.
-
-2.3. Message Attributes
-
- In addition to message text, each message has several attributes
- associated with it. These attributes may be retrieved individually
- or in conjunction with other attributes or message texts.
-
-2.3.1. Message Numbers
-
- Messages in IMAP4rev1 are accessed by one of two numbers; the unique
- identifier and the message sequence number.
-
-2.3.1.1. Unique Identifier (UID) Message Attribute
-
- A 32-bit value assigned to each message, which when used with the
- unique identifier validity value (see below) forms a 64-bit value
-
-
-
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-
-
- that is permanently guaranteed not to refer to any other message in
- the mailbox. Unique identifiers are assigned in a strictly ascending
- fashion in the mailbox; as each message is added to the mailbox it is
- assigned a higher UID than the message(s) which were added
- previously.
-
- Unlike message sequence numbers, unique identifiers are not
- necessarily contiguous. Unique identifiers also persist across
- sessions. This permits a client to resynchronize its state from a
- previous session with the server (e.g. disconnected or offline access
- clients); this is discussed further in [IMAP-DISC].
-
- Associated with every mailbox is a unique identifier validity value,
- which is sent in an UIDVALIDITY response code in an OK untagged
- response at mailbox selection time. If unique identifiers from an
- earlier session fail to persist to this session, the unique
- identifier validity value MUST be greater than the one used in the
- earlier session.
-
- Note: Unique identifiers MUST be strictly ascending in the mailbox
- at all times. If the physical message store is re-ordered by a
- non-IMAP agent, this requires that the unique identifiers in the
- mailbox be regenerated, since the former unique identifers are no
- longer strictly ascending as a result of the re-ordering. Another
- instance in which unique identifiers are regenerated is if the
- message store has no mechanism to store unique identifiers.
- Although this specification recognizes that this may be
- unavoidable in certain server environments, it STRONGLY ENCOURAGES
- message store implementation techniques that avoid this problem.
-
- Another cause of non-persistance is if the mailbox is deleted and
- a new mailbox with the same name is created at a later date, Since
- the name is the same, a client may not know that this is a new
- mailbox unless the unique identifier validity is different. A
- good value to use for the unique identifier validity value is a
- 32-bit representation of the creation date/time of the mailbox.
- It is alright to use a constant such as 1, but only if it
- guaranteed that unique identifiers will never be reused, even in
- the case of a mailbox being deleted (or renamed) and a new mailbox
- by the same name created at some future time.
-
- The unique identifier of a message MUST NOT change during the
- session, and SHOULD NOT change between sessions. However, if it is
- not possible to preserve the unique identifier of a message in a
- subsequent session, each subsequent session MUST have a new unique
- identifier validity value that is larger than any that was used
- previously.
-
-
-
-
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-
-
-2.3.1.2. Message Sequence Number Message Attribute
-
- A relative position from 1 to the number of messages in the mailbox.
- This position MUST be ordered by ascending unique identifier. As
- each new message is added, it is assigned a message sequence number
- that is 1 higher than the number of messages in the mailbox before
- that new message was added.
-
- Message sequence numbers can be reassigned during the session. For
- example, when a message is permanently removed (expunged) from the
- mailbox, the message sequence number for all subsequent messages is
- decremented. Similarly, a new message can be assigned a message
- sequence number that was once held by some other message prior to an
- expunge.
-
- In addition to accessing messages by relative position in the
- mailbox, message sequence numbers can be used in mathematical
- calculations. For example, if an untagged "EXISTS 11" is received,
- and previously an untagged "8 EXISTS" was received, three new
- messages have arrived with message sequence numbers of 9, 10, and 11.
- Another example; if message 287 in a 523 message mailbox has UID
- 12345, there are exactly 286 messages which have lesser UIDs and 236
- messages which have greater UIDs.
-
-2.3.2. Flags Message Attribute
-
- A list of zero or more named tokens associated with the message. A
- flag is set by its addition to this list, and is cleared by its
- removal. There are two types of flags in IMAP4rev1. A flag of
- either type may be permanent or session-only.
-
- A system flag is a flag name that is pre-defined in this
- specification. All system flags begin with "\". Certain system
- flags (\Deleted and \Seen) have special semantics described
- elsewhere. The currently-defined system flags are:
-
- \Seen Message has been read
-
- \Answered Message has been answered
-
- \Flagged Message is "flagged" for urgent/special attention
-
- \Deleted Message is "deleted" for removal by later EXPUNGE
-
- \Draft Message has not completed composition (marked as a
- draft).
-
-
-
-
-
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-RFC 2060 IMAP4rev1 December 1996
-
-
- \Recent Message is "recently" arrived in this mailbox. This
- session is the first session to have been notified
- about this message; subsequent sessions will not see
- \Recent set for this message. This flag can not be
- altered by the client.
-
- If it is not possible to determine whether or not
- this session is the first session to be notified
- about a message, then that message SHOULD be
- considered recent.
-
- If multiple connections have the same mailbox
- selected simultaneously, it is undefined which of
- these connections will see newly-arrives messages
- with \Recent set and which will see it without
- \Recent set.
-
- A keyword is defined by the server implementation. Keywords do
- not begin with "\". Servers MAY permit the client to define new
- keywords in the mailbox (see the description of the
- PERMANENTFLAGS response code for more information).
-
- A flag may be permanent or session-only on a per-flag basis.
- Permanent flags are those which the client can add or remove
- from the message flags permanently; that is, subsequent sessions
- will see any change in permanent flags. Changes to session
- flags are valid only in that session.
-
- Note: The \Recent system flag is a special case of a
- session flag. \Recent can not be used as an argument in a
- STORE command, and thus can not be changed at all.
-
-2.3.3. Internal Date Message Attribute
-
- The internal date and time of the message on the server. This is not
- the date and time in the [RFC-822] header, but rather a date and time
- which reflects when the message was received. In the case of
- messages delivered via [SMTP], this SHOULD be the date and time of
- final delivery of the message as defined by [SMTP]. In the case of
- messages delivered by the IMAP4rev1 COPY command, this SHOULD be the
- internal date and time of the source message. In the case of
- messages delivered by the IMAP4rev1 APPEND command, this SHOULD be
- the date and time as specified in the APPEND command description.
- All other cases are implementation defined.
-
-
-
-
-
-
-
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-
-
-2.3.4. [RFC-822] Size Message Attribute
-
- The number of octets in the message, as expressed in [RFC-822]
- format.
-
-2.3.5. Envelope Structure Message Attribute
-
- A parsed representation of the [RFC-822] envelope information (not to
- be confused with an [SMTP] envelope) of the message.
-
-2.3.6. Body Structure Message Attribute
-
- A parsed representation of the [MIME-IMB] body structure information
- of the message.
-
-2.4. Message Texts
-
- In addition to being able to fetch the full [RFC-822] text of a
- message, IMAP4rev1 permits the fetching of portions of the full
- message text. Specifically, it is possible to fetch the [RFC-822]
- message header, [RFC-822] message body, a [MIME-IMB] body part, or a
- [MIME-IMB] header.
-
-3. State and Flow Diagram
-
- An IMAP4rev1 server is in one of four states. Most commands are
- valid in only certain states. It is a protocol error for the client
- to attempt a command while the command is in an inappropriate state.
- In this case, a server will respond with a BAD or NO (depending upon
- server implementation) command completion result.
-
-3.1. Non-Authenticated State
-
- In non-authenticated state, the client MUST supply authentication
- credentials before most commands will be permitted. This state is
- entered when a connection starts unless the connection has been pre-
- authenticated.
-
-3.2. Authenticated State
-
- In authenticated state, the client is authenticated and MUST select a
- mailbox to access before commands that affect messages will be
- permitted. This state is entered when a pre-authenticated connection
- starts, when acceptable authentication credentials have been
- provided, or after an error in selecting a mailbox.
-
-
-
-
-
-
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-
-3.3. Selected State
-
- In selected state, a mailbox has been selected to access. This state
- is entered when a mailbox has been successfully selected.
-
-3.4. Logout State
-
- In logout state, the connection is being terminated, and the server
- will close the connection. This state can be entered as a result of
- a client request or by unilateral server decision.
-
- +--------------------------------------+
- |initial connection and server greeting|
- +--------------------------------------+
- || (1) || (2) || (3)
- VV || ||
- +-----------------+ || ||
- |non-authenticated| || ||
- +-----------------+ || ||
- || (7) || (4) || ||
- || VV VV ||
- || +----------------+ ||
- || | authenticated |<=++ ||
- || +----------------+ || ||
- || || (7) || (5) || (6) ||
- || || VV || ||
- || || +--------+ || ||
- || || |selected|==++ ||
- || || +--------+ ||
- || || || (7) ||
- VV VV VV VV
- +--------------------------------------+
- | logout and close connection |
- +--------------------------------------+
-
- (1) connection without pre-authentication (OK greeting)
- (2) pre-authenticated connection (PREAUTH greeting)
- (3) rejected connection (BYE greeting)
- (4) successful LOGIN or AUTHENTICATE command
- (5) successful SELECT or EXAMINE command
- (6) CLOSE command, or failed SELECT or EXAMINE command
- (7) LOGOUT command, server shutdown, or connection closed
-
-4. Data Formats
-
- IMAP4rev1 uses textual commands and responses. Data in IMAP4rev1 can
- be in one of several forms: atom, number, string, parenthesized list,
- or NIL.
-
-
-
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-
-
-4.1. Atom
-
- An atom consists of one or more non-special characters.
-
-4.2. Number
-
- A number consists of one or more digit characters, and represents a
- numeric value.
-
-4.3. String
-
- A string is in one of two forms: literal and quoted string. The
- literal form is the general form of string. The quoted string form
- is an alternative that avoids the overhead of processing a literal at
- the cost of limitations of characters that can be used in a quoted
- string.
-
- A literal is a sequence of zero or more octets (including CR and LF),
- prefix-quoted with an octet count in the form of an open brace ("{"),
- the number of octets, close brace ("}"), and CRLF. In the case of
- literals transmitted from server to client, the CRLF is immediately
- followed by the octet data. In the case of literals transmitted from
- client to server, the client MUST wait to receive a command
- continuation request (described later in this document) before
- sending the octet data (and the remainder of the command).
-
- A quoted string is a sequence of zero or more 7-bit characters,
- excluding CR and LF, with double quote (<">) characters at each end.
-
- The empty string is represented as either "" (a quoted string with
- zero characters between double quotes) or as {0} followed by CRLF (a
- literal with an octet count of 0).
-
- Note: Even if the octet count is 0, a client transmitting a
- literal MUST wait to receive a command continuation request.
-
-4.3.1. 8-bit and Binary Strings
-
- 8-bit textual and binary mail is supported through the use of a
- [MIME-IMB] content transfer encoding. IMAP4rev1 implementations MAY
- transmit 8-bit or multi-octet characters in literals, but SHOULD do
- so only when the [CHARSET] is identified.
-
-
-
-
-
-
-
-
-
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-
-
- Although a BINARY body encoding is defined, unencoded binary strings
- are not permitted. A "binary string" is any string with NUL
- characters. Implementations MUST encode binary data into a textual
- form such as BASE64 before transmitting the data. A string with an
- excessive amount of CTL characters MAY also be considered to be
- binary.
-
-4.4. Parenthesized List
-
- Data structures are represented as a "parenthesized list"; a sequence
- of data items, delimited by space, and bounded at each end by
- parentheses. A parenthesized list can contain other parenthesized
- lists, using multiple levels of parentheses to indicate nesting.
-
- The empty list is represented as () -- a parenthesized list with no
- members.
-
-4.5. NIL
-
- The special atom "NIL" represents the non-existence of a particular
- data item that is represented as a string or parenthesized list, as
- distinct from the empty string "" or the empty parenthesized list ().
-
-5. Operational Considerations
-
-5.1. Mailbox Naming
-
- The interpretation of mailbox names is implementation-dependent.
- However, the case-insensitive mailbox name INBOX is a special name
- reserved to mean "the primary mailbox for this user on this server".
-
-5.1.1. Mailbox Hierarchy Naming
-
- If it is desired to export hierarchical mailbox names, mailbox names
- MUST be left-to-right hierarchical using a single character to
- separate levels of hierarchy. The same hierarchy separator character
- is used for all levels of hierarchy within a single name.
-
-5.1.2. Mailbox Namespace Naming Convention
-
- By convention, the first hierarchical element of any mailbox name
- which begins with "#" identifies the "namespace" of the remainder of
- the name. This makes it possible to disambiguate between different
- types of mailbox stores, each of which have their own namespaces.
-
-
-
-
-
-
-
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-
-
- For example, implementations which offer access to USENET
- newsgroups MAY use the "#news" namespace to partition the USENET
- newsgroup namespace from that of other mailboxes. Thus, the
- comp.mail.misc newsgroup would have an mailbox name of
- "#news.comp.mail.misc", and the name "comp.mail.misc" could refer
- to a different object (e.g. a user's private mailbox).
-
-5.1.3. Mailbox International Naming Convention
-
- By convention, international mailbox names are specified using a
- modified version of the UTF-7 encoding described in [UTF-7]. The
- purpose of these modifications is to correct the following problems
- with UTF-7:
-
- 1) UTF-7 uses the "+" character for shifting; this conflicts with
- the common use of "+" in mailbox names, in particular USENET
- newsgroup names.
-
- 2) UTF-7's encoding is BASE64 which uses the "/" character; this
- conflicts with the use of "/" as a popular hierarchy delimiter.
-
- 3) UTF-7 prohibits the unencoded usage of "\"; this conflicts with
- the use of "\" as a popular hierarchy delimiter.
-
- 4) UTF-7 prohibits the unencoded usage of "~"; this conflicts with
- the use of "~" in some servers as a home directory indicator.
-
- 5) UTF-7 permits multiple alternate forms to represent the same
- string; in particular, printable US-ASCII chararacters can be
- represented in encoded form.
-
- In modified UTF-7, printable US-ASCII characters except for "&"
- represent themselves; that is, characters with octet values 0x20-0x25
- and 0x27-0x7e. The character "&" (0x26) is represented by the two-
- octet sequence "&-".
-
- All other characters (octet values 0x00-0x1f, 0x7f-0xff, and all
- Unicode 16-bit octets) are represented in modified BASE64, with a
- further modification from [UTF-7] that "," is used instead of "/".
- Modified BASE64 MUST NOT be used to represent any printing US-ASCII
- character which can represent itself.
-
- "&" is used to shift to modified BASE64 and "-" to shift back to US-
- ASCII. All names start in US-ASCII, and MUST end in US-ASCII (that
- is, a name that ends with a Unicode 16-bit octet MUST end with a "-
- ").
-
-
-
-
-
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-
-
- For example, here is a mailbox name which mixes English, Japanese,
- and Chinese text: ~peter/mail/&ZeVnLIqe-/&U,BTFw-
-
-5.2. Mailbox Size and Message Status Updates
-
- At any time, a server can send data that the client did not request.
- Sometimes, such behavior is REQUIRED. For example, agents other than
- the server MAY add messages to the mailbox (e.g. new mail delivery),
- change the flags of message in the mailbox (e.g. simultaneous access
- to the same mailbox by multiple agents), or even remove messages from
- the mailbox. A server MUST send mailbox size updates automatically
- if a mailbox size change is observed during the processing of a
- command. A server SHOULD send message flag updates automatically,
- without requiring the client to request such updates explicitly.
- Special rules exist for server notification of a client about the
- removal of messages to prevent synchronization errors; see the
- description of the EXPUNGE response for more detail.
-
- Regardless of what implementation decisions a client makes on
- remembering data from the server, a client implementation MUST record
- mailbox size updates. It MUST NOT assume that any command after
- initial mailbox selection will return the size of the mailbox.
-
-5.3. Response when no Command in Progress
-
- Server implementations are permitted to send an untagged response
- (except for EXPUNGE) while there is no command in progress. Server
- implementations that send such responses MUST deal with flow control
- considerations. Specifically, they MUST either (1) verify that the
- size of the data does not exceed the underlying transport's available
- window size, or (2) use non-blocking writes.
-
-5.4. Autologout Timer
-
- If a server has an inactivity autologout timer, that timer MUST be of
- at least 30 minutes' duration. The receipt of ANY command from the
- client during that interval SHOULD suffice to reset the autologout
- timer.
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-5.5. Multiple Commands in Progress
-
- The client MAY send another command without waiting for the
- completion result response of a command, subject to ambiguity rules
- (see below) and flow control constraints on the underlying data
- stream. Similarly, a server MAY begin processing another command
- before processing the current command to completion, subject to
- ambiguity rules. However, any command continuation request responses
- and command continuations MUST be negotiated before any subsequent
- command is initiated.
-
- The exception is if an ambiguity would result because of a command
- that would affect the results of other commands. Clients MUST NOT
- send multiple commands without waiting if an ambiguity would result.
- If the server detects a possible ambiguity, it MUST execute commands
- to completion in the order given by the client.
-
- The most obvious example of ambiguity is when a command would affect
- the results of another command; for example, a FETCH of a message's
- flags and a STORE of that same message's flags.
-
- A non-obvious ambiguity occurs with commands that permit an untagged
- EXPUNGE response (commands other than FETCH, STORE, and SEARCH),
- since an untagged EXPUNGE response can invalidate sequence numbers in
- a subsequent command. This is not a problem for FETCH, STORE, or
- SEARCH commands because servers are prohibited from sending EXPUNGE
- responses while any of those commands are in progress. Therefore, if
- the client sends any command other than FETCH, STORE, or SEARCH, it
- MUST wait for a response before sending a command with message
- sequence numbers.
-
- For example, the following non-waiting command sequences are invalid:
-
- FETCH + NOOP + STORE
- STORE + COPY + FETCH
- COPY + COPY
- CHECK + FETCH
-
- The following are examples of valid non-waiting command sequences:
-
- FETCH + STORE + SEARCH + CHECK
- STORE + COPY + EXPUNGE
-
-6. Client Commands
-
- IMAP4rev1 commands are described in this section. Commands are
- organized by the state in which the command is permitted. Commands
- which are permitted in multiple states are listed in the minimum
-
-
-
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-
-
- permitted state (for example, commands valid in authenticated and
- selected state are listed in the authenticated state commands).
-
- Command arguments, identified by "Arguments:" in the command
- descriptions below, are described by function, not by syntax. The
- precise syntax of command arguments is described in the Formal Syntax
- section.
-
- Some commands cause specific server responses to be returned; these
- are identified by "Responses:" in the command descriptions below.
- See the response descriptions in the Responses section for
- information on these responses, and the Formal Syntax section for the
- precise syntax of these responses. It is possible for server data to
- be transmitted as a result of any command; thus, commands that do not
- specifically require server data specify "no specific responses for
- this command" instead of "none".
-
- The "Result:" in the command description refers to the possible
- tagged status responses to a command, and any special interpretation
- of these status responses.
-
-6.1. Client Commands - Any State
-
- The following commands are valid in any state: CAPABILITY, NOOP, and
- LOGOUT.
-
-6.1.1. CAPABILITY Command
-
- Arguments: none
-
- Responses: REQUIRED untagged response: CAPABILITY
-
- Result: OK - capability completed
- BAD - command unknown or arguments invalid
-
- The CAPABILITY command requests a listing of capabilities that the
- server supports. The server MUST send a single untagged
- CAPABILITY response with "IMAP4rev1" as one of the listed
- capabilities before the (tagged) OK response. This listing of
- capabilities is not dependent upon connection state or user. It
- is therefore not necessary to issue a CAPABILITY command more than
- once in a connection.
-
-
-
-
-
-
-
-
-
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-
-
- A capability name which begins with "AUTH=" indicates that the
- server supports that particular authentication mechanism. All
- such names are, by definition, part of this specification. For
- example, the authorization capability for an experimental
- "blurdybloop" authenticator would be "AUTH=XBLURDYBLOOP" and not
- "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP".
-
- Other capability names refer to extensions, revisions, or
- amendments to this specification. See the documentation of the
- CAPABILITY response for additional information. No capabilities,
- beyond the base IMAP4rev1 set defined in this specification, are
- enabled without explicit client action to invoke the capability.
-
- See the section entitled "Client Commands -
- Experimental/Expansion" for information about the form of site or
- implementation-specific capabilities.
-
- Example: C: abcd CAPABILITY
- S: * CAPABILITY IMAP4rev1 AUTH=KERBEROS_V4
- S: abcd OK CAPABILITY completed
-
-6.1.2. NOOP Command
-
- Arguments: none
-
- Responses: no specific responses for this command (but see below)
-
- Result: OK - noop completed
- BAD - command unknown or arguments invalid
-
- The NOOP command always succeeds. It does nothing.
-
- Since any command can return a status update as untagged data, the
- NOOP command can be used as a periodic poll for new messages or
- message status updates during a period of inactivity. The NOOP
- command can also be used to reset any inactivity autologout timer
- on the server.
-
- Example: C: a002 NOOP
- S: a002 OK NOOP completed
- . . .
- C: a047 NOOP
- S: * 22 EXPUNGE
- S: * 23 EXISTS
- S: * 3 RECENT
- S: * 14 FETCH (FLAGS (\Seen \Deleted))
- S: a047 OK NOOP completed
-
-
-
-
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-
-
-6.1.3. LOGOUT Command
-
- Arguments: none
-
- Responses: REQUIRED untagged response: BYE
-
- Result: OK - logout completed
- BAD - command unknown or arguments invalid
-
- The LOGOUT command informs the server that the client is done with
- the connection. The server MUST send a BYE untagged response
- before the (tagged) OK response, and then close the network
- connection.
-
- Example: C: A023 LOGOUT
- S: * BYE IMAP4rev1 Server logging out
- S: A023 OK LOGOUT completed
- (Server and client then close the connection)
-
-6.2. Client Commands - Non-Authenticated State
-
- In non-authenticated state, the AUTHENTICATE or LOGIN command
- establishes authentication and enter authenticated state. The
- AUTHENTICATE command provides a general mechanism for a variety of
- authentication techniques, whereas the LOGIN command uses the
- traditional user name and plaintext password pair.
-
- Server implementations MAY allow non-authenticated access to certain
- mailboxes. The convention is to use a LOGIN command with the userid
- "anonymous". A password is REQUIRED. It is implementation-dependent
- what requirements, if any, are placed on the password and what access
- restrictions are placed on anonymous users.
-
- Once authenticated (including as anonymous), it is not possible to
- re-enter non-authenticated state.
-
- In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
- the following commands are valid in non-authenticated state:
- AUTHENTICATE and LOGIN.
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-6.2.1. AUTHENTICATE Command
-
- Arguments: authentication mechanism name
-
- Responses: continuation data can be requested
-
- Result: OK - authenticate completed, now in authenticated state
- NO - authenticate failure: unsupported authentication
- mechanism, credentials rejected
- BAD - command unknown or arguments invalid,
- authentication exchange cancelled
-
- The AUTHENTICATE command indicates an authentication mechanism,
- such as described in [IMAP-AUTH], to the server. If the server
- supports the requested authentication mechanism, it performs an
- authentication protocol exchange to authenticate and identify the
- client. It MAY also negotiate an OPTIONAL protection mechanism
- for subsequent protocol interactions. If the requested
- authentication mechanism is not supported, the server SHOULD
- reject the AUTHENTICATE command by sending a tagged NO response.
-
- The authentication protocol exchange consists of a series of
- server challenges and client answers that are specific to the
- authentication mechanism. A server challenge consists of a
- command continuation request response with the "+" token followed
- by a BASE64 encoded string. The client answer consists of a line
- consisting of a BASE64 encoded string. If the client wishes to
- cancel an authentication exchange, it issues a line with a single
- "*". If the server receives such an answer, it MUST reject the
- AUTHENTICATE command by sending a tagged BAD response.
-
- A protection mechanism provides integrity and privacy protection
- to the connection. If a protection mechanism is negotiated, it is
- applied to all subsequent data sent over the connection. The
- protection mechanism takes effect immediately following the CRLF
- that concludes the authentication exchange for the client, and the
- CRLF of the tagged OK response for the server. Once the
- protection mechanism is in effect, the stream of command and
- response octets is processed into buffers of ciphertext. Each
- buffer is transferred over the connection as a stream of octets
- prepended with a four octet field in network byte order that
- represents the length of the following data. The maximum
- ciphertext buffer length is defined by the protection mechanism.
-
- Authentication mechanisms are OPTIONAL. Protection mechanisms are
- also OPTIONAL; an authentication mechanism MAY be implemented
- without any protection mechanism. If an AUTHENTICATE command
- fails with a NO response, the client MAY try another
-
-
-
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-
-
- authentication mechanism by issuing another AUTHENTICATE command,
- or MAY attempt to authenticate by using the LOGIN command. In
- other words, the client MAY request authentication types in
- decreasing order of preference, with the LOGIN command as a last
- resort.
-
- Example: S: * OK KerberosV4 IMAP4rev1 Server
- C: A001 AUTHENTICATE KERBEROS_V4
- S: + AmFYig==
- C: BAcAQU5EUkVXLkNNVS5FRFUAOCAsho84kLN3/IJmrMG+25a4DT
- +nZImJjnTNHJUtxAA+o0KPKfHEcAFs9a3CL5Oebe/ydHJUwYFd
- WwuQ1MWiy6IesKvjL5rL9WjXUb9MwT9bpObYLGOKi1Qh
- S: + or//EoAADZI=
- C: DiAF5A4gA+oOIALuBkAAmw==
- S: A001 OK Kerberos V4 authentication successful
-
- Note: the line breaks in the first client answer are for editorial
- clarity and are not in real authenticators.
-
-6.2.2. LOGIN Command
-
- Arguments: user name
- password
-
- Responses: no specific responses for this command
-
- Result: OK - login completed, now in authenticated state
- NO - login failure: user name or password rejected
- BAD - command unknown or arguments invalid
-
- The LOGIN command identifies the client to the server and carries
- the plaintext password authenticating this user.
-
- Example: C: a001 LOGIN SMITH SESAME
- S: a001 OK LOGIN completed
-
-6.3. Client Commands - Authenticated State
-
- In authenticated state, commands that manipulate mailboxes as atomic
- entities are permitted. Of these commands, the SELECT and EXAMINE
- commands will select a mailbox for access and enter selected state.
-
- In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
- the following commands are valid in authenticated state: SELECT,
- EXAMINE, CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, LSUB,
- STATUS, and APPEND.
-
-
-
-
-
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-
-
-6.3.1. SELECT Command
-
- Arguments: mailbox name
-
- Responses: REQUIRED untagged responses: FLAGS, EXISTS, RECENT
- OPTIONAL OK untagged responses: UNSEEN, PERMANENTFLAGS
-
- Result: OK - select completed, now in selected state
- NO - select failure, now in authenticated state: no
- such mailbox, can't access mailbox
- BAD - command unknown or arguments invalid
-
- The SELECT command selects a mailbox so that messages in the
- mailbox can be accessed. Before returning an OK to the client,
- the server MUST send the following untagged data to the client:
-
- FLAGS Defined flags in the mailbox. See the description
- of the FLAGS response for more detail.
-
- <n> EXISTS The number of messages in the mailbox. See the
- description of the EXISTS response for more detail.
-
- <n> RECENT The number of messages with the \Recent flag set.
- See the description of the RECENT response for more
- detail.
-
- OK [UIDVALIDITY <n>]
- The unique identifier validity value. See the
- description of the UID command for more detail.
-
- to define the initial state of the mailbox at the client.
-
- The server SHOULD also send an UNSEEN response code in an OK
- untagged response, indicating the message sequence number of the
- first unseen message in the mailbox.
-
- If the client can not change the permanent state of one or more of
- the flags listed in the FLAGS untagged response, the server SHOULD
- send a PERMANENTFLAGS response code in an OK untagged response,
- listing the flags that the client can change permanently.
-
- Only one mailbox can be selected at a time in a connection;
- simultaneous access to multiple mailboxes requires multiple
- connections. The SELECT command automatically deselects any
- currently selected mailbox before attempting the new selection.
- Consequently, if a mailbox is selected and a SELECT command that
- fails is attempted, no mailbox is selected.
-
-
-
-
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-
-
- If the client is permitted to modify the mailbox, the server
- SHOULD prefix the text of the tagged OK response with the
- "[READ-WRITE]" response code.
-
- If the client is not permitted to modify the mailbox but is
- permitted read access, the mailbox is selected as read-only, and
- the server MUST prefix the text of the tagged OK response to
- SELECT with the "[READ-ONLY]" response code. Read-only access
- through SELECT differs from the EXAMINE command in that certain
- read-only mailboxes MAY permit the change of permanent state on a
- per-user (as opposed to global) basis. Netnews messages marked in
- a server-based .newsrc file are an example of such per-user
- permanent state that can be modified with read-only mailboxes.
-
- Example: C: A142 SELECT INBOX
- S: * 172 EXISTS
- S: * 1 RECENT
- S: * OK [UNSEEN 12] Message 12 is first unseen
- S: * OK [UIDVALIDITY 3857529045] UIDs valid
- S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
- S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited
- S: A142 OK [READ-WRITE] SELECT completed
-
-6.3.2. EXAMINE Command
-
- Arguments: mailbox name
-
- Responses: REQUIRED untagged responses: FLAGS, EXISTS, RECENT
- OPTIONAL OK untagged responses: UNSEEN, PERMANENTFLAGS
-
- Result: OK - examine completed, now in selected state
- NO - examine failure, now in authenticated state: no
- such mailbox, can't access mailbox
- BAD - command unknown or arguments invalid
-
- The EXAMINE command is identical to SELECT and returns the same
- output; however, the selected mailbox is identified as read-only.
- No changes to the permanent state of the mailbox, including
- per-user state, are permitted.
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
- The text of the tagged OK response to the EXAMINE command MUST
- begin with the "[READ-ONLY]" response code.
-
- Example: C: A932 EXAMINE blurdybloop
- S: * 17 EXISTS
- S: * 2 RECENT
- S: * OK [UNSEEN 8] Message 8 is first unseen
- S: * OK [UIDVALIDITY 3857529045] UIDs valid
- S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
- S: * OK [PERMANENTFLAGS ()] No permanent flags permitted
- S: A932 OK [READ-ONLY] EXAMINE completed
-
-6.3.3. CREATE Command
-
- Arguments: mailbox name
-
- Responses: no specific responses for this command
-
- Result: OK - create completed
- NO - create failure: can't create mailbox with that name
- BAD - command unknown or arguments invalid
-
- The CREATE command creates a mailbox with the given name. An OK
- response is returned only if a new mailbox with that name has been
- created. It is an error to attempt to create INBOX or a mailbox
- with a name that refers to an extant mailbox. Any error in
- creation will return a tagged NO response.
-
- If the mailbox name is suffixed with the server's hierarchy
- separator character (as returned from the server by a LIST
- command), this is a declaration that the client intends to create
- mailbox names under this name in the hierarchy. Server
- implementations that do not require this declaration MUST ignore
- it.
-
- If the server's hierarchy separator character appears elsewhere in
- the name, the server SHOULD create any superior hierarchical names
- that are needed for the CREATE command to complete successfully.
- In other words, an attempt to create "foo/bar/zap" on a server in
- which "/" is the hierarchy separator character SHOULD create foo/
- and foo/bar/ if they do not already exist.
-
- If a new mailbox is created with the same name as a mailbox which
- was deleted, its unique identifiers MUST be greater than any
- unique identifiers used in the previous incarnation of the mailbox
- UNLESS the new incarnation has a different unique identifier
- validity value. See the description of the UID command for more
- detail.
-
-
-
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-
-
- Example: C: A003 CREATE owatagusiam/
- S: A003 OK CREATE completed
- C: A004 CREATE owatagusiam/blurdybloop
- S: A004 OK CREATE completed
-
- Note: the interpretation of this example depends on whether "/"
- was returned as the hierarchy separator from LIST. If "/" is the
- hierarchy separator, a new level of hierarchy named "owatagusiam"
- with a member called "blurdybloop" is created. Otherwise, two
- mailboxes at the same hierarchy level are created.
-
-6.3.4. DELETE Command
-
- Arguments: mailbox name
-
- Responses: no specific responses for this command
-
- Result: OK - delete completed
- NO - delete failure: can't delete mailbox with that name
- BAD - command unknown or arguments invalid
-
- The DELETE command permanently removes the mailbox with the given
- name. A tagged OK response is returned only if the mailbox has
- been deleted. It is an error to attempt to delete INBOX or a
- mailbox name that does not exist.
-
- The DELETE command MUST NOT remove inferior hierarchical names.
- For example, if a mailbox "foo" has an inferior "foo.bar"
- (assuming "." is the hierarchy delimiter character), removing
- "foo" MUST NOT remove "foo.bar". It is an error to attempt to
- delete a name that has inferior hierarchical names and also has
- the \Noselect mailbox name attribute (see the description of the
- LIST response for more details).
-
- It is permitted to delete a name that has inferior hierarchical
- names and does not have the \Noselect mailbox name attribute. In
- this case, all messages in that mailbox are removed, and the name
- will acquire the \Noselect mailbox name attribute.
-
- The value of the highest-used unique identifier of the deleted
- mailbox MUST be preserved so that a new mailbox created with the
- same name will not reuse the identifiers of the former
- incarnation, UNLESS the new incarnation has a different unique
- identifier validity value. See the description of the UID command
- for more detail.
-
-
-
-
-
-
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-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- Examples: C: A682 LIST "" *
- S: * LIST () "/" blurdybloop
- S: * LIST (\Noselect) "/" foo
- S: * LIST () "/" foo/bar
- S: A682 OK LIST completed
- C: A683 DELETE blurdybloop
- S: A683 OK DELETE completed
- C: A684 DELETE foo
- S: A684 NO Name "foo" has inferior hierarchical names
- C: A685 DELETE foo/bar
- S: A685 OK DELETE Completed
- C: A686 LIST "" *
- S: * LIST (\Noselect) "/" foo
- S: A686 OK LIST completed
- C: A687 DELETE foo
- S: A687 OK DELETE Completed
-
-
- C: A82 LIST "" *
- S: * LIST () "." blurdybloop
- S: * LIST () "." foo
- S: * LIST () "." foo.bar
- S: A82 OK LIST completed
- C: A83 DELETE blurdybloop
- S: A83 OK DELETE completed
- C: A84 DELETE foo
- S: A84 OK DELETE Completed
- C: A85 LIST "" *
- S: * LIST () "." foo.bar
- S: A85 OK LIST completed
- C: A86 LIST "" %
- S: * LIST (\Noselect) "." foo
- S: A86 OK LIST completed
-
-6.3.5. RENAME Command
-
- Arguments: existing mailbox name
- new mailbox name
-
- Responses: no specific responses for this command
-
- Result: OK - rename completed
- NO - rename failure: can't rename mailbox with that name,
- can't rename to mailbox with that name
- BAD - command unknown or arguments invalid
-
- The RENAME command changes the name of a mailbox. A tagged OK
- response is returned only if the mailbox has been renamed. It is
-
-
-
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-
-
- an error to attempt to rename from a mailbox name that does not
- exist or to a mailbox name that already exists. Any error in
- renaming will return a tagged NO response.
-
- If the name has inferior hierarchical names, then the inferior
- hierarchical names MUST also be renamed. For example, a rename of
- "foo" to "zap" will rename "foo/bar" (assuming "/" is the
- hierarchy delimiter character) to "zap/bar".
-
- The value of the highest-used unique identifier of the old mailbox
- name MUST be preserved so that a new mailbox created with the same
- name will not reuse the identifiers of the former incarnation,
- UNLESS the new incarnation has a different unique identifier
- validity value. See the description of the UID command for more
- detail.
-
- Renaming INBOX is permitted, and has special behavior. It moves
- all messages in INBOX to a new mailbox with the given name,
- leaving INBOX empty. If the server implementation supports
- inferior hierarchical names of INBOX, these are unaffected by a
- rename of INBOX.
-
- Examples: C: A682 LIST "" *
- S: * LIST () "/" blurdybloop
- S: * LIST (\Noselect) "/" foo
- S: * LIST () "/" foo/bar
- S: A682 OK LIST completed
- C: A683 RENAME blurdybloop sarasoop
- S: A683 OK RENAME completed
- C: A684 RENAME foo zowie
- S: A684 OK RENAME Completed
- C: A685 LIST "" *
- S: * LIST () "/" sarasoop
- S: * LIST (\Noselect) "/" zowie
- S: * LIST () "/" zowie/bar
- S: A685 OK LIST completed
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
- C: Z432 LIST "" *
- S: * LIST () "." INBOX
- S: * LIST () "." INBOX.bar
- S: Z432 OK LIST completed
- C: Z433 RENAME INBOX old-mail
- S: Z433 OK RENAME completed
- C: Z434 LIST "" *
- S: * LIST () "." INBOX
- S: * LIST () "." INBOX.bar
- S: * LIST () "." old-mail
- S: Z434 OK LIST completed
-
-6.3.6. SUBSCRIBE Command
-
- Arguments: mailbox
-
- Responses: no specific responses for this command
-
- Result: OK - subscribe completed
- NO - subscribe failure: can't subscribe to that name
- BAD - command unknown or arguments invalid
-
- The SUBSCRIBE command adds the specified mailbox name to the
- server's set of "active" or "subscribed" mailboxes as returned by
- the LSUB command. This command returns a tagged OK response only
- if the subscription is successful.
-
- A server MAY validate the mailbox argument to SUBSCRIBE to verify
- that it exists. However, it MUST NOT unilaterally remove an
- existing mailbox name from the subscription list even if a mailbox
- by that name no longer exists.
-
- Note: this requirement is because some server sites may routinely
- remove a mailbox with a well-known name (e.g. "system-alerts")
- after its contents expire, with the intention of recreating it
- when new contents are appropriate.
-
- Example: C: A002 SUBSCRIBE #news.comp.mail.mime
- S: A002 OK SUBSCRIBE completed
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-6.3.7. UNSUBSCRIBE Command
-
- Arguments: mailbox name
-
- Responses: no specific responses for this command
-
- Result: OK - unsubscribe completed
- NO - unsubscribe failure: can't unsubscribe that name
- BAD - command unknown or arguments invalid
-
- The UNSUBSCRIBE command removes the specified mailbox name from
- the server's set of "active" or "subscribed" mailboxes as returned
- by the LSUB command. This command returns a tagged OK response
- only if the unsubscription is successful.
-
- Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime
- S: A002 OK UNSUBSCRIBE completed
-
-6.3..8. LIST Command
-
- Arguments: reference name
- mailbox name with possible wildcards
-
- Responses: untagged responses: LIST
-
- Result: OK - list completed
- NO - list failure: can't list that reference or name
- BAD - command unknown or arguments invalid
-
- The LIST command returns a subset of names from the complete set
- of all names available to the client. Zero or more untagged LIST
- replies are returned, containing the name attributes, hierarchy
- delimiter, and name; see the description of the LIST reply for
- more detail.
-
- The LIST command SHOULD return its data quickly, without undue
- delay. For example, it SHOULD NOT go to excess trouble to
- calculate \Marked or \Unmarked status or perform other processing;
- if each name requires 1 second of processing, then a list of 1200
- names would take 20 minutes!
-
- An empty ("" string) reference name argument indicates that the
- mailbox name is interpreted as by SELECT. The returned mailbox
- names MUST match the supplied mailbox name pattern. A non-empty
- reference name argument is the name of a mailbox or a level of
- mailbox hierarchy, and indicates a context in which the mailbox
- name is interpreted in an implementation-defined manner.
-
-
-
-
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-
-
- An empty ("" string) mailbox name argument is a special request to
- return the hierarchy delimiter and the root name of the name given
- in the reference. The value returned as the root MAY be null if
- the reference is non-rooted or is null. In all cases, the
- hierarchy delimiter is returned. This permits a client to get the
- hierarchy delimiter even when no mailboxes by that name currently
- exist.
-
- The reference and mailbox name arguments are interpreted, in an
- implementation-dependent fashion, into a canonical form that
- represents an unambiguous left-to-right hierarchy. The returned
- mailbox names will be in the interpreted form.
-
- Any part of the reference argument that is included in the
- interpreted form SHOULD prefix the interpreted form. It SHOULD
- also be in the same form as the reference name argument. This
- rule permits the client to determine if the returned mailbox name
- is in the context of the reference argument, or if something about
- the mailbox argument overrode the reference argument. Without
- this rule, the client would have to have knowledge of the server's
- naming semantics including what characters are "breakouts" that
- override a naming context.
-
- For example, here are some examples of how references and mailbox
- names might be interpreted on a UNIX-based server:
-
- Reference Mailbox Name Interpretation
- ------------ ------------ --------------
- ~smith/Mail/ foo.* ~smith/Mail/foo.*
- archive/ % archive/%
- #news. comp.mail.* #news.comp.mail.*
- ~smith/Mail/ /usr/doc/foo /usr/doc/foo
- archive/ ~fred/Mail/* ~fred/Mail/*
-
- The first three examples demonstrate interpretations in the
- context of the reference argument. Note that "~smith/Mail" SHOULD
- NOT be transformed into something like "/u2/users/smith/Mail", or
- it would be impossible for the client to determine that the
- interpretation was in the context of the reference.
-
- The character "*" is a wildcard, and matches zero or more
- characters at this position. The character "%" is similar to "*",
- but it does not match a hierarchy delimiter. If the "%" wildcard
- is the last character of a mailbox name argument, matching levels
- of hierarchy are also returned. If these levels of hierarchy are
- not also selectable mailboxes, they are returned with the
- \Noselect mailbox name attribute (see the description of the LIST
- response for more details).
-
-
-
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-
-
- Server implementations are permitted to "hide" otherwise
- accessible mailboxes from the wildcard characters, by preventing
- certain characters or names from matching a wildcard in certain
- situations. For example, a UNIX-based server might restrict the
- interpretation of "*" so that an initial "/" character does not
- match.
-
- The special name INBOX is included in the output from LIST, if
- INBOX is supported by this server for this user and if the
- uppercase string "INBOX" matches the interpreted reference and
- mailbox name arguments with wildcards as described above. The
- criteria for omitting INBOX is whether SELECT INBOX will return
- failure; it is not relevant whether the user's real INBOX resides
- on this or some other server.
-
- Example: C: A101 LIST "" ""
- S: * LIST (\Noselect) "/" ""
- S: A101 OK LIST Completed
- C: A102 LIST #news.comp.mail.misc ""
- S: * LIST (\Noselect) "." #news.
- S: A102 OK LIST Completed
- C: A103 LIST /usr/staff/jones ""
- S: * LIST (\Noselect) "/" /
- S: A103 OK LIST Completed
- C: A202 LIST ~/Mail/ %
- S: * LIST (\Noselect) "/" ~/Mail/foo
- S: * LIST () "/" ~/Mail/meetings
- S: A202 OK LIST completed
-
-6.3.9. LSUB Command
-
- Arguments: reference name
- mailbox name with possible wildcards
-
- Responses: untagged responses: LSUB
-
- Result: OK - lsub completed
- NO - lsub failure: can't list that reference or name
- BAD - command unknown or arguments invalid
-
- The LSUB command returns a subset of names from the set of names
- that the user has declared as being "active" or "subscribed".
- Zero or more untagged LSUB replies are returned. The arguments to
- LSUB are in the same form as those for LIST.
-
- A server MAY validate the subscribed names to see if they still
- exist. If a name does not exist, it SHOULD be flagged with the
- \Noselect attribute in the LSUB response. The server MUST NOT
-
-
-
-Crispin Standards Track [Page 32]
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-
-
- unilaterally remove an existing mailbox name from the subscription
- list even if a mailbox by that name no longer exists.
-
- Example: C: A002 LSUB "#news." "comp.mail.*"
- S: * LSUB () "." #news.comp.mail.mime
- S: * LSUB () "." #news.comp.mail.misc
- S: A002 OK LSUB completed
-
-6.3.10. STATUS Command
-
- Arguments: mailbox name
- status data item names
-
- Responses: untagged responses: STATUS
-
- Result: OK - status completed
- NO - status failure: no status for that name
- BAD - command unknown or arguments invalid
-
- The STATUS command requests the status of the indicated mailbox.
- It does not change the currently selected mailbox, nor does it
- affect the state of any messages in the queried mailbox (in
- particular, STATUS MUST NOT cause messages to lose the \Recent
- flag).
-
- The STATUS command provides an alternative to opening a second
- IMAP4rev1 connection and doing an EXAMINE command on a mailbox to
- query that mailbox's status without deselecting the current
- mailbox in the first IMAP4rev1 connection.
-
- Unlike the LIST command, the STATUS command is not guaranteed to
- be fast in its response. In some implementations, the server is
- obliged to open the mailbox read-only internally to obtain certain
- status information. Also unlike the LIST command, the STATUS
- command does not accept wildcards.
-
- The currently defined status data items that can be requested are:
-
- MESSAGES The number of messages in the mailbox.
-
- RECENT The number of messages with the \Recent flag set.
-
- UIDNEXT The next UID value that will be assigned to a new
- message in the mailbox. It is guaranteed that this
- value will not change unless new messages are added
- to the mailbox; and that it will change when new
- messages are added even if those new messages are
- subsequently expunged.
-
-
-
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-
-
- UIDVALIDITY The unique identifier validity value of the
- mailbox.
-
- UNSEEN The number of messages which do not have the \Seen
- flag set.
-
-
- Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES)
- S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292)
- S: A042 OK STATUS completed
-
-6.3.11. APPEND Command
-
- Arguments: mailbox name
- OPTIONAL flag parenthesized list
- OPTIONAL date/time string
- message literal
-
- Responses: no specific responses for this command
-
- Result: OK - append completed
- NO - append error: can't append to that mailbox, error
- in flags or date/time or message text
- BAD - command unknown or arguments invalid
-
- The APPEND command appends the literal argument as a new message
- to the end of the specified destination mailbox. This argument
- SHOULD be in the format of an [RFC-822] message. 8-bit characters
- are permitted in the message. A server implementation that is
- unable to preserve 8-bit data properly MUST be able to reversibly
- convert 8-bit APPEND data to 7-bit using a [MIME-IMB] content
- transfer encoding.
-
- Note: There MAY be exceptions, e.g. draft messages, in which
- required [RFC-822] header lines are omitted in the message literal
- argument to APPEND. The full implications of doing so MUST be
- understood and carefully weighed.
-
- If a flag parenthesized list is specified, the flags SHOULD be set in
- the resulting message; otherwise, the flag list of the resulting
- message is set empty by default.
-
- If a date_time is specified, the internal date SHOULD be set in the
- resulting message; otherwise, the internal date of the resulting
- message is set to the current date and time by default.
-
-
-
-
-
-
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-
-
- If the append is unsuccessful for any reason, the mailbox MUST be
- restored to its state before the APPEND attempt; no partial appending
- is permitted.
-
- If the destination mailbox does not exist, a server MUST return an
- error, and MUST NOT automatically create the mailbox. Unless it is
- certain that the destination mailbox can not be created, the server
- MUST send the response code "[TRYCREATE]" as the prefix of the text
- of the tagged NO response. This gives a hint to the client that it
- can attempt a CREATE command and retry the APPEND if the CREATE is
- successful.
-
- If the mailbox is currently selected, the normal new mail actions
- SHOULD occur. Specifically, the server SHOULD notify the client
- immediately via an untagged EXISTS response. If the server does not
- do so, the client MAY issue a NOOP command (or failing that, a CHECK
- command) after one or more APPEND commands.
-
- Example: C: A003 APPEND saved-messages (\Seen) {310}
- C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)
- C: From: Fred Foobar <foobar@Blurdybloop.COM>
- C: Subject: afternoon meeting
- C: To: mooch@owatagu.siam.edu
- C: Message-Id: <B27397-0100000@Blurdybloop.COM>
- C: MIME-Version: 1.0
- C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
- C:
- C: Hello Joe, do you think we can meet at 3:30 tomorrow?
- C:
- S: A003 OK APPEND completed
-
- Note: the APPEND command is not used for message delivery, because
- it does not provide a mechanism to transfer [SMTP] envelope
- information.
-
-6.4. Client Commands - Selected State
-
- In selected state, commands that manipulate messages in a mailbox are
- permitted.
-
- In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
- and the authenticated state commands (SELECT, EXAMINE, CREATE,
- DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, LSUB, STATUS, and
- APPEND), the following commands are valid in the selected state:
- CHECK, CLOSE, EXPUNGE, SEARCH, FETCH, STORE, COPY, and UID.
-
-
-
-
-
-
-Crispin Standards Track [Page 35]
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-
-
-6.4.1. CHECK Command
-
- Arguments: none
-
- Responses: no specific responses for this command
-
- Result: OK - check completed
- BAD - command unknown or arguments invalid
-
- The CHECK command requests a checkpoint of the currently selected
- mailbox. A checkpoint refers to any implementation-dependent
- housekeeping associated with the mailbox (e.g. resolving the
- server's in-memory state of the mailbox with the state on its
- disk) that is not normally executed as part of each command. A
- checkpoint MAY take a non-instantaneous amount of real time to
- complete. If a server implementation has no such housekeeping
- considerations, CHECK is equivalent to NOOP.
-
- There is no guarantee that an EXISTS untagged response will happen
- as a result of CHECK. NOOP, not CHECK, SHOULD be used for new
- mail polling.
-
- Example: C: FXXZ CHECK
- S: FXXZ OK CHECK Completed
-
-6.4.2. CLOSE Command
-
- Arguments: none
-
- Responses: no specific responses for this command
-
- Result: OK - close completed, now in authenticated state
- NO - close failure: no mailbox selected
- BAD - command unknown or arguments invalid
-
- The CLOSE command permanently removes from the currently selected
- mailbox all messages that have the \Deleted flag set, and returns
- to authenticated state from selected state. No untagged EXPUNGE
- responses are sent.
-
- No messages are removed, and no error is given, if the mailbox is
- selected by an EXAMINE command or is otherwise selected read-only.
-
- Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT
- command MAY be issued without previously issuing a CLOSE command.
- The SELECT, EXAMINE, and LOGOUT commands implicitly close the
- currently selected mailbox without doing an expunge. However,
- when many messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT
-
-
-
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-\f
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-
-
- sequence is considerably faster than an EXPUNGE-LOGOUT or
- EXPUNGE-SELECT because no untagged EXPUNGE responses (which the
- client would probably ignore) are sent.
-
- Example: C: A341 CLOSE
- S: A341 OK CLOSE completed
-
-6.4.3. EXPUNGE Command
-
- Arguments: none
-
- Responses: untagged responses: EXPUNGE
-
- Result: OK - expunge completed
- NO - expunge failure: can't expunge (e.g. permission
- denied)
- BAD - command unknown or arguments invalid
-
- The EXPUNGE command permanently removes from the currently
- selected mailbox all messages that have the \Deleted flag set.
- Before returning an OK to the client, an untagged EXPUNGE response
- is sent for each message that is removed.
-
- Example: C: A202 EXPUNGE
- S: * 3 EXPUNGE
- S: * 3 EXPUNGE
- S: * 5 EXPUNGE
- S: * 8 EXPUNGE
- S: A202 OK EXPUNGE completed
-
- Note: in this example, messages 3, 4, 7, and 11 had the
- \Deleted flag set. See the description of the EXPUNGE
- response for further explanation.
-
-6.4.4. SEARCH Command
-
- Arguments: OPTIONAL [CHARSET] specification
- searching criteria (one or more)
-
- Responses: REQUIRED untagged response: SEARCH
-
- Result: OK - search completed
- NO - search error: can't search that [CHARSET] or
- criteria
- BAD - command unknown or arguments invalid
-
-
-
-
-
-
-Crispin Standards Track [Page 37]
-\f
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-
-
- The SEARCH command searches the mailbox for messages that match
- the given searching criteria. Searching criteria consist of one
- or more search keys. The untagged SEARCH response from the server
- contains a listing of message sequence numbers corresponding to
- those messages that match the searching criteria.
-
- When multiple keys are specified, the result is the intersection
- (AND function) of all the messages that match those keys. For
- example, the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers
- to all deleted messages from Smith that were placed in the mailbox
- since February 1, 1994. A search key can also be a parenthesized
- list of one or more search keys (e.g. for use with the OR and NOT
- keys).
-
- Server implementations MAY exclude [MIME-IMB] body parts with
- terminal content media types other than TEXT and MESSAGE from
- consideration in SEARCH matching.
-
- The OPTIONAL [CHARSET] specification consists of the word
- "CHARSET" followed by a registered [CHARSET]. It indicates the
- [CHARSET] of the strings that appear in the search criteria.
- [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in
- [RFC-822]/[MIME-IMB] headers, MUST be decoded before comparing
- text in a [CHARSET] other than US-ASCII. US-ASCII MUST be
- supported; other [CHARSET]s MAY be supported. If the server does
- not support the specified [CHARSET], it MUST return a tagged NO
- response (not a BAD).
-
- In all search keys that use strings, a message matches the key if
- the string is a substring of the field. The matching is case-
- insensitive.
-
- The defined search keys are as follows. Refer to the Formal
- Syntax section for the precise syntactic definitions of the
- arguments.
-
- <message set> Messages with message sequence numbers
- corresponding to the specified message sequence
- number set
-
- ALL All messages in the mailbox; the default initial
- key for ANDing.
-
- ANSWERED Messages with the \Answered flag set.
-
- BCC <string> Messages that contain the specified string in the
- envelope structure's BCC field.
-
-
-
-
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-
-
- BEFORE <date> Messages whose internal date is earlier than the
- specified date.
-
- BODY <string> Messages that contain the specified string in the
- body of the message.
-
- CC <string> Messages that contain the specified string in the
- envelope structure's CC field.
-
- DELETED Messages with the \Deleted flag set.
-
- DRAFT Messages with the \Draft flag set.
-
- FLAGGED Messages with the \Flagged flag set.
-
- FROM <string> Messages that contain the specified string in the
- envelope structure's FROM field.
-
- HEADER <field-name> <string>
- Messages that have a header with the specified
- field-name (as defined in [RFC-822]) and that
- contains the specified string in the [RFC-822]
- field-body.
-
- KEYWORD <flag> Messages with the specified keyword set.
-
- LARGER <n> Messages with an [RFC-822] size larger than the
- specified number of octets.
-
- NEW Messages that have the \Recent flag set but not the
- \Seen flag. This is functionally equivalent to
- "(RECENT UNSEEN)".
-
- NOT <search-key>
- Messages that do not match the specified search
- key.
-
- OLD Messages that do not have the \Recent flag set.
- This is functionally equivalent to "NOT RECENT" (as
- opposed to "NOT NEW").
-
- ON <date> Messages whose internal date is within the
- specified date.
-
- OR <search-key1> <search-key2>
- Messages that match either search key.
-
- RECENT Messages that have the \Recent flag set.
-
-
-
-Crispin Standards Track [Page 39]
-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- SEEN Messages that have the \Seen flag set.
-
- SENTBEFORE <date>
- Messages whose [RFC-822] Date: header is earlier
- than the specified date.
-
- SENTON <date> Messages whose [RFC-822] Date: header is within the
- specified date.
-
- SENTSINCE <date>
- Messages whose [RFC-822] Date: header is within or
- later than the specified date.
-
- SINCE <date> Messages whose internal date is within or later
- than the specified date.
-
- SMALLER <n> Messages with an [RFC-822] size smaller than the
- specified number of octets.
-
- SUBJECT <string>
- Messages that contain the specified string in the
- envelope structure's SUBJECT field.
-
- TEXT <string> Messages that contain the specified string in the
- header or body of the message.
-
- TO <string> Messages that contain the specified string in the
- envelope structure's TO field.
-
- UID <message set>
- Messages with unique identifiers corresponding to
- the specified unique identifier set.
-
- UNANSWERED Messages that do not have the \Answered flag set.
-
- UNDELETED Messages that do not have the \Deleted flag set.
-
- UNDRAFT Messages that do not have the \Draft flag set.
-
- UNFLAGGED Messages that do not have the \Flagged flag set.
-
- UNKEYWORD <flag>
- Messages that do not have the specified keyword
- set.
-
- UNSEEN Messages that do not have the \Seen flag set.
-
-
-
-
-
-Crispin Standards Track [Page 40]
-\f
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-
-
- Example: C: A282 SEARCH FLAGGED SINCE 1-Feb-1994 NOT FROM "Smith"
- S: * SEARCH 2 84 882
- S: A282 OK SEARCH completed
-
-6.4.5. FETCH Command
-
- Arguments: message set
- message data item names
-
- Responses: untagged responses: FETCH
-
- Result: OK - fetch completed
- NO - fetch error: can't fetch that data
- BAD - command unknown or arguments invalid
-
- The FETCH command retrieves data associated with a message in the
- mailbox. The data items to be fetched can be either a single atom
- or a parenthesized list.
-
- The currently defined data items that can be fetched are:
-
- ALL Macro equivalent to: (FLAGS INTERNALDATE
- RFC822.SIZE ENVELOPE)
-
- BODY Non-extensible form of BODYSTRUCTURE.
-
- BODY[<section>]<<partial>>
- The text of a particular body section. The section
- specification is a set of zero or more part
- specifiers delimited by periods. A part specifier
- is either a part number or one of the following:
- HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, and
- TEXT. An empty section specification refers to the
- entire message, including the header.
-
- Every message has at least one part number.
- Non-[MIME-IMB] messages, and non-multipart
- [MIME-IMB] messages with no encapsulated message,
- only have a part 1.
-
- Multipart messages are assigned consecutive part
- numbers, as they occur in the message. If a
- particular part is of type message or multipart,
- its parts MUST be indicated by a period followed by
- the part number within that nested multipart part.
-
-
-
-
-
-
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-
-
- A part of type MESSAGE/RFC822 also has nested part
- numbers, referring to parts of the MESSAGE part's
- body.
-
- The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and
- TEXT part specifiers can be the sole part specifier
- or can be prefixed by one or more numeric part
- specifiers, provided that the numeric part
- specifier refers to a part of type MESSAGE/RFC822.
- The MIME part specifier MUST be prefixed by one or
- more numeric part specifiers.
-
- The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT
- part specifiers refer to the [RFC-822] header of
- the message or of an encapsulated [MIME-IMT]
- MESSAGE/RFC822 message. HEADER.FIELDS and
- HEADER.FIELDS.NOT are followed by a list of
- field-name (as defined in [RFC-822]) names, and
- return a subset of the header. The subset returned
- by HEADER.FIELDS contains only those header fields
- with a field-name that matches one of the names in
- the list; similarly, the subset returned by
- HEADER.FIELDS.NOT contains only the header fields
- with a non-matching field-name. The field-matching
- is case-insensitive but otherwise exact. In all
- cases, the delimiting blank line between the header
- and the body is always included.
-
- The MIME part specifier refers to the [MIME-IMB]
- header for this part.
-
- The TEXT part specifier refers to the text body of
- the message, omitting the [RFC-822] header.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
- Here is an example of a complex message
- with some of its part specifiers:
-
- HEADER ([RFC-822] header of the message)
- TEXT MULTIPART/MIXED
- 1 TEXT/PLAIN
- 2 APPLICATION/OCTET-STREAM
- 3 MESSAGE/RFC822
- 3.HEADER ([RFC-822] header of the message)
- 3.TEXT ([RFC-822] text body of the message)
- 3.1 TEXT/PLAIN
- 3.2 APPLICATION/OCTET-STREAM
- 4 MULTIPART/MIXED
- 4.1 IMAGE/GIF
- 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF)
- 4.2 MESSAGE/RFC822
- 4.2.HEADER ([RFC-822] header of the message)
- 4.2.TEXT ([RFC-822] text body of the message)
- 4.2.1 TEXT/PLAIN
- 4.2.2 MULTIPART/ALTERNATIVE
- 4.2.2.1 TEXT/PLAIN
- 4.2.2.2 TEXT/RICHTEXT
-
-
- It is possible to fetch a substring of the
- designated text. This is done by appending an open
- angle bracket ("<"), the octet position of the
- first desired octet, a period, the maximum number
- of octets desired, and a close angle bracket (">")
- to the part specifier. If the starting octet is
- beyond the end of the text, an empty string is
- returned.
-
- Any partial fetch that attempts to read beyond the
- end of the text is truncated as appropriate. A
- partial fetch that starts at octet 0 is returned as
- a partial fetch, even if this truncation happened.
-
- Note: this means that BODY[]<0.2048> of a
- 1500-octet message will return BODY[]<0>
- with a literal of size 1500, not BODY[].
-
- Note: a substring fetch of a
- HEADER.FIELDS or HEADER.FIELDS.NOT part
- specifier is calculated after subsetting
- the header.
-
-
-
-
-
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-
-
- The \Seen flag is implicitly set; if this causes
- the flags to change they SHOULD be included as part
- of the FETCH responses.
-
- BODY.PEEK[<section>]<<partial>>
- An alternate form of BODY[<section>] that does not
- implicitly set the \Seen flag.
-
- BODYSTRUCTURE The [MIME-IMB] body structure of the message. This
- is computed by the server by parsing the [MIME-IMB]
- header fields in the [RFC-822] header and
- [MIME-IMB] headers.
-
- ENVELOPE The envelope structure of the message. This is
- computed by the server by parsing the [RFC-822]
- header into the component parts, defaulting various
- fields as necessary.
-
- FAST Macro equivalent to: (FLAGS INTERNALDATE
- RFC822.SIZE)
-
- FLAGS The flags that are set for this message.
-
- FULL Macro equivalent to: (FLAGS INTERNALDATE
- RFC822.SIZE ENVELOPE BODY)
-
- INTERNALDATE The internal date of the message.
-
- RFC822 Functionally equivalent to BODY[], differing in the
- syntax of the resulting untagged FETCH data (RFC822
- is returned).
-
- RFC822.HEADER Functionally equivalent to BODY.PEEK[HEADER],
- differing in the syntax of the resulting untagged
- FETCH data (RFC822.HEADER is returned).
-
- RFC822.SIZE The [RFC-822] size of the message.
-
- RFC822.TEXT Functionally equivalent to BODY[TEXT], differing in
- the syntax of the resulting untagged FETCH data
- (RFC822.TEXT is returned).
-
- UID The unique identifier for the message.
-
-
-
-
-
-
-
-
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-
-
- Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)])
- S: * 2 FETCH ....
- S: * 3 FETCH ....
- S: * 4 FETCH ....
- S: A654 OK FETCH completed
-
-6.4.6. STORE Command
-
- Arguments: message set
- message data item name
- value for message data item
-
- Responses: untagged responses: FETCH
-
- Result: OK - store completed
- NO - store error: can't store that data
- BAD - command unknown or arguments invalid
-
- The STORE command alters data associated with a message in the
- mailbox. Normally, STORE will return the updated value of the
- data with an untagged FETCH response. A suffix of ".SILENT" in
- the data item name prevents the untagged FETCH, and the server
- SHOULD assume that the client has determined the updated value
- itself or does not care about the updated value.
-
- Note: regardless of whether or not the ".SILENT" suffix was
- used, the server SHOULD send an untagged FETCH response if a
- change to a message's flags from an external source is
- observed. The intent is that the status of the flags is
- determinate without a race condition.
-
- The currently defined data items that can be stored are:
-
- FLAGS <flag list>
- Replace the flags for the message with the
- argument. The new value of the flags are returned
- as if a FETCH of those flags was done.
-
- FLAGS.SILENT <flag list>
- Equivalent to FLAGS, but without returning a new
- value.
-
- +FLAGS <flag list>
- Add the argument to the flags for the message. The
- new value of the flags are returned as if a FETCH
- of those flags was done.
-
-
-
-
-
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-
-
- +FLAGS.SILENT <flag list>
- Equivalent to +FLAGS, but without returning a new
- value.
-
- -FLAGS <flag list>
- Remove the argument from the flags for the message.
- The new value of the flags are returned as if a
- FETCH of those flags was done.
-
- -FLAGS.SILENT <flag list>
- Equivalent to -FLAGS, but without returning a new
- value.
-
- Example: C: A003 STORE 2:4 +FLAGS (\Deleted)
- S: * 2 FETCH FLAGS (\Deleted \Seen)
- S: * 3 FETCH FLAGS (\Deleted)
- S: * 4 FETCH FLAGS (\Deleted \Flagged \Seen)
- S: A003 OK STORE completed
-
-6.4.7. COPY Command
-
- Arguments: message set
- mailbox name
-
- Responses: no specific responses for this command
-
- Result: OK - copy completed
- NO - copy error: can't copy those messages or to that
- name
- BAD - command unknown or arguments invalid
-
- The COPY command copies the specified message(s) to the end of the
- specified destination mailbox. The flags and internal date of the
- message(s) SHOULD be preserved in the copy.
-
- If the destination mailbox does not exist, a server SHOULD return
- an error. It SHOULD NOT automatically create the mailbox. Unless
- it is certain that the destination mailbox can not be created, the
- server MUST send the response code "[TRYCREATE]" as the prefix of
- the text of the tagged NO response. This gives a hint to the
- client that it can attempt a CREATE command and retry the COPY if
- the CREATE is successful.
-
-
-
-
-
-
-
-
-
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-
-
- If the COPY command is unsuccessful for any reason, server
- implementations MUST restore the destination mailbox to its state
- before the COPY attempt.
-
- Example: C: A003 COPY 2:4 MEETING
- S: A003 OK COPY completed
-
-6.4.8. UID Command
-
- Arguments: command name
- command arguments
-
- Responses: untagged responses: FETCH, SEARCH
-
- Result: OK - UID command completed
- NO - UID command error
- BAD - command unknown or arguments invalid
-
- The UID command has two forms. In the first form, it takes as its
- arguments a COPY, FETCH, or STORE command with arguments
- appropriate for the associated command. However, the numbers in
- the message set argument are unique identifiers instead of message
- sequence numbers.
-
- In the second form, the UID command takes a SEARCH command with
- SEARCH command arguments. The interpretation of the arguments is
- the same as with SEARCH; however, the numbers returned in a SEARCH
- response for a UID SEARCH command are unique identifiers instead
- of message sequence numbers. For example, the command UID SEARCH
- 1:100 UID 443:557 returns the unique identifiers corresponding to
- the intersection of the message sequence number set 1:100 and the
- UID set 443:557.
-
- Message set ranges are permitted; however, there is no guarantee
- that unique identifiers be contiguous. A non-existent unique
- identifier within a message set range is ignored without any error
- message generated.
-
- The number after the "*" in an untagged FETCH response is always a
- message sequence number, not a unique identifier, even for a UID
- command response. However, server implementations MUST implicitly
- include the UID message data item as part of any FETCH response
- caused by a UID command, regardless of whether a UID was specified
- as a message data item to the FETCH.
-
-
-
-
-
-
-
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-
-
- Example: C: A999 UID FETCH 4827313:4828442 FLAGS
- S: * 23 FETCH (FLAGS (\Seen) UID 4827313)
- S: * 24 FETCH (FLAGS (\Seen) UID 4827943)
- S: * 25 FETCH (FLAGS (\Seen) UID 4828442)
- S: A999 UID FETCH completed
-
-6.5. Client Commands - Experimental/Expansion
-
-6.5.1. X<atom> Command
-
- Arguments: implementation defined
-
- Responses: implementation defined
-
- Result: OK - command completed
- NO - failure
- BAD - command unknown or arguments invalid
-
- Any command prefixed with an X is an experimental command.
- Commands which are not part of this specification, a standard or
- standards-track revision of this specification, or an IESG-
- approved experimental protocol, MUST use the X prefix.
-
- Any added untagged responses issued by an experimental command
- MUST also be prefixed with an X. Server implementations MUST NOT
- send any such untagged responses, unless the client requested it
- by issuing the associated experimental command.
-
- Example: C: a441 CAPABILITY
- S: * CAPABILITY IMAP4rev1 AUTH=KERBEROS_V4 XPIG-LATIN
- S: a441 OK CAPABILITY completed
- C: A442 XPIG-LATIN
- S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay
- S: A442 OK XPIG-LATIN ompleted-cay
-
-7. Server Responses
-
- Server responses are in three forms: status responses, server data,
- and command continuation request. The information contained in a
- server response, identified by "Contents:" in the response
- descriptions below, is described by function, not by syntax. The
- precise syntax of server responses is described in the Formal Syntax
- section.
-
- The client MUST be prepared to accept any response at all times.
-
-
-
-
-
-
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-\f
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-
-
- Status responses can be tagged or untagged. Tagged status responses
- indicate the completion result (OK, NO, or BAD status) of a client
- command, and have a tag matching the command.
-
- Some status responses, and all server data, are untagged. An
- untagged response is indicated by the token "*" instead of a tag.
- Untagged status responses indicate server greeting, or server status
- that does not indicate the completion of a command (for example, an
- impending system shutdown alert). For historical reasons, untagged
- server data responses are also called "unsolicited data", although
- strictly speaking only unilateral server data is truly "unsolicited".
-
- Certain server data MUST be recorded by the client when it is
- received; this is noted in the description of that data. Such data
- conveys critical information which affects the interpretation of all
- subsequent commands and responses (e.g. updates reflecting the
- creation or destruction of messages).
-
- Other server data SHOULD be recorded for later reference; if the
- client does not need to record the data, or if recording the data has
- no obvious purpose (e.g. a SEARCH response when no SEARCH command is
- in progress), the data SHOULD be ignored.
-
- An example of unilateral untagged server data occurs when the IMAP
- connection is in selected state. In selected state, the server
- checks the mailbox for new messages as part of command execution.
- Normally, this is part of the execution of every command; hence, a
- NOOP command suffices to check for new messages. If new messages are
- found, the server sends untagged EXISTS and RECENT responses
- reflecting the new size of the mailbox. Server implementations that
- offer multiple simultaneous access to the same mailbox SHOULD also
- send appropriate unilateral untagged FETCH and EXPUNGE responses if
- another agent changes the state of any message flags or expunges any
- messages.
-
- Command continuation request responses use the token "+" instead of a
- tag. These responses are sent by the server to indicate acceptance
- of an incomplete client command and readiness for the remainder of
- the command.
-
-7.1. Server Responses - Status Responses
-
- Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD
- may be tagged or untagged. PREAUTH and BYE are always untagged.
-
- Status responses MAY include an OPTIONAL "response code". A response
- code consists of data inside square brackets in the form of an atom,
- possibly followed by a space and arguments. The response code
-
-
-
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-\f
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-
-
- contains additional information or status codes for client software
- beyond the OK/NO/BAD condition, and are defined when there is a
- specific action that a client can take based upon the additional
- information.
-
- The currently defined response codes are:
-
- ALERT The human-readable text contains a special alert
- that MUST be presented to the user in a fashion
- that calls the user's attention to the message.
-
- NEWNAME Followed by a mailbox name and a new mailbox name.
- A SELECT or EXAMINE is failing because the target
- mailbox name no longer exists because it was
- renamed to the new mailbox name. This is a hint to
- the client that the operation can succeed if the
- SELECT or EXAMINE is reissued with the new mailbox
- name.
-
- PARSE The human-readable text represents an error in
- parsing the [RFC-822] header or [MIME-IMB] headers
- of a message in the mailbox.
-
- PERMANENTFLAGS Followed by a parenthesized list of flags,
- indicates which of the known flags that the client
- can change permanently. Any flags that are in the
- FLAGS untagged response, but not the PERMANENTFLAGS
- list, can not be set permanently. If the client
- attempts to STORE a flag that is not in the
- PERMANENTFLAGS list, the server will either reject
- it with a NO reply or store the state for the
- remainder of the current session only. The
- PERMANENTFLAGS list can also include the special
- flag \*, which indicates that it is possible to
- create new keywords by attempting to store those
- flags in the mailbox.
-
- READ-ONLY The mailbox is selected read-only, or its access
- while selected has changed from read-write to
- read-only.
-
- READ-WRITE The mailbox is selected read-write, or its access
- while selected has changed from read-only to
- read-write.
-
-
-
-
-
-
-
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-
-
- TRYCREATE An APPEND or COPY attempt is failing because the
- target mailbox does not exist (as opposed to some
- other reason). This is a hint to the client that
- the operation can succeed if the mailbox is first
- created by the CREATE command.
-
- UIDVALIDITY Followed by a decimal number, indicates the unique
- identifier validity value.
-
- UNSEEN Followed by a decimal number, indicates the number
- of the first message without the \Seen flag set.
-
- Additional response codes defined by particular client or server
- implementations SHOULD be prefixed with an "X" until they are
- added to a revision of this protocol. Client implementations
- SHOULD ignore response codes that they do not recognize.
-
-7.1.1. OK Response
-
- Contents: OPTIONAL response code
- human-readable text
-
- The OK response indicates an information message from the server.
- When tagged, it indicates successful completion of the associated
- command. The human-readable text MAY be presented to the user as
- an information message. The untagged form indicates an
- information-only message; the nature of the information MAY be
- indicated by a response code.
-
- The untagged form is also used as one of three possible greetings
- at connection startup. It indicates that the connection is not
- yet authenticated and that a LOGIN command is needed.
-
- Example: S: * OK IMAP4rev1 server ready
- C: A001 LOGIN fred blurdybloop
- S: * OK [ALERT] System shutdown in 10 minutes
- S: A001 OK LOGIN Completed
-
-7.1.2. NO Response
-
- Contents: OPTIONAL response code
- human-readable text
-
- The NO response indicates an operational error message from the
- server. When tagged, it indicates unsuccessful completion of the
- associated command. The untagged form indicates a warning; the
- command can still complete successfully. The human-readable text
- describes the condition.
-
-
-
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-\f
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-
-
- Example: C: A222 COPY 1:2 owatagusiam
- S: * NO Disk is 98% full, please delete unnecessary data
- S: A222 OK COPY completed
- C: A223 COPY 3:200 blurdybloop
- S: * NO Disk is 98% full, please delete unnecessary data
- S: * NO Disk is 99% full, please delete unnecessary data
- S: A223 NO COPY failed: disk is full
-
-7.1.3. BAD Response
-
- Contents: OPTIONAL response code
- human-readable text
-
- The BAD response indicates an error message from the server. When
- tagged, it reports a protocol-level error in the client's command;
- the tag indicates the command that caused the error. The untagged
- form indicates a protocol-level error for which the associated
- command can not be determined; it can also indicate an internal
- server failure. The human-readable text describes the condition.
-
- Example: C: ...very long command line...
- S: * BAD Command line too long
- C: ...empty line...
- S: * BAD Empty command line
- C: A443 EXPUNGE
- S: * BAD Disk crash, attempting salvage to a new disk!
- S: * OK Salvage successful, no data lost
- S: A443 OK Expunge completed
-
-7.1.4. PREAUTH Response
-
- Contents: OPTIONAL response code
- human-readable text
-
- The PREAUTH response is always untagged, and is one of three
- possible greetings at connection startup. It indicates that the
- connection has already been authenticated by external means and
- thus no LOGIN command is needed.
-
- Example: S: * PREAUTH IMAP4rev1 server logged in as Smith
-
-7.1.5. BYE Response
-
- Contents: OPTIONAL response code
- human-readable text
-
-
-
-
-
-
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-\f
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-
-
- The BYE response is always untagged, and indicates that the server
- is about to close the connection. The human-readable text MAY be
- displayed to the user in a status report by the client. The BYE
- response is sent under one of four conditions:
-
- 1) as part of a normal logout sequence. The server will close
- the connection after sending the tagged OK response to the
- LOGOUT command.
-
- 2) as a panic shutdown announcement. The server closes the
- connection immediately.
-
- 3) as an announcement of an inactivity autologout. The server
- closes the connection immediately.
-
- 4) as one of three possible greetings at connection startup,
- indicating that the server is not willing to accept a
- connection from this client. The server closes the
- connection immediately.
-
- The difference between a BYE that occurs as part of a normal
- LOGOUT sequence (the first case) and a BYE that occurs because of
- a failure (the other three cases) is that the connection closes
- immediately in the failure case.
-
- Example: S: * BYE Autologout; idle for too long
-
-7.2. Server Responses - Server and Mailbox Status
-
- These responses are always untagged. This is how server and mailbox
- status data are transmitted from the server to the client. Many of
- these responses typically result from a command with the same name.
-
-7.2.1. CAPABILITY Response
-
- Contents: capability listing
-
- The CAPABILITY response occurs as a result of a CAPABILITY
- command. The capability listing contains a space-separated
- listing of capability names that the server supports. The
- capability listing MUST include the atom "IMAP4rev1".
-
- A capability name which begins with "AUTH=" indicates that the
- server supports that particular authentication mechanism.
-
-
-
-
-
-
-
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-
-
- Other capability names indicate that the server supports an
- extension, revision, or amendment to the IMAP4rev1 protocol.
- Server responses MUST conform to this document until the client
- issues a command that uses the associated capability.
-
- Capability names MUST either begin with "X" or be standard or
- standards-track IMAP4rev1 extensions, revisions, or amendments
- registered with IANA. A server MUST NOT offer unregistered or
- non-standard capability names, unless such names are prefixed with
- an "X".
-
- Client implementations SHOULD NOT require any capability name
- other than "IMAP4rev1", and MUST ignore any unknown capability
- names.
-
- Example: S: * CAPABILITY IMAP4rev1 AUTH=KERBEROS_V4 XPIG-LATIN
-
-7.2.2. LIST Response
-
- Contents: name attributes
- hierarchy delimiter
- name
-
- The LIST response occurs as a result of a LIST command. It
- returns a single name that matches the LIST specification. There
- can be multiple LIST responses for a single LIST command.
-
- Four name attributes are defined:
-
- \Noinferiors It is not possible for any child levels of
- hierarchy to exist under this name; no child levels
- exist now and none can be created in the future.
-
- \Noselect It is not possible to use this name as a selectable
- mailbox.
-
- \Marked The mailbox has been marked "interesting" by the
- server; the mailbox probably contains messages that
- have been added since the last time the mailbox was
- selected.
-
- \Unmarked The mailbox does not contain any additional
- messages since the last time the mailbox was
- selected.
-
- If it is not feasible for the server to determine whether the
- mailbox is "interesting" or not, or if the name is a \Noselect
- name, the server SHOULD NOT send either \Marked or \Unmarked.
-
-
-
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-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- The hierarchy delimiter is a character used to delimit levels of
- hierarchy in a mailbox name. A client can use it to create child
- mailboxes, and to search higher or lower levels of naming
- hierarchy. All children of a top-level hierarchy node MUST use
- the same separator character. A NIL hierarchy delimiter means
- that no hierarchy exists; the name is a "flat" name.
-
- The name represents an unambiguous left-to-right hierarchy, and
- MUST be valid for use as a reference in LIST and LSUB commands.
- Unless \Noselect is indicated, the name MUST also be valid as an
- argument for commands, such as SELECT, that accept mailbox
- names.
-
- Example: S: * LIST (\Noselect) "/" ~/Mail/foo
-
-7.2.3. LSUB Response
-
- Contents: name attributes
- hierarchy delimiter
- name
-
- The LSUB response occurs as a result of an LSUB command. It
- returns a single name that matches the LSUB specification. There
- can be multiple LSUB responses for a single LSUB command. The
- data is identical in format to the LIST response.
-
- Example: S: * LSUB () "." #news.comp.mail.misc
-
-7.2.4 STATUS Response
-
- Contents: name
- status parenthesized list
-
- The STATUS response occurs as a result of an STATUS command. It
- returns the mailbox name that matches the STATUS specification and
- the requested mailbox status information.
-
- Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292)
-
-7.2.5. SEARCH Response
-
- Contents: zero or more numbers
-
-
-
-
-
-
-
-
-
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-
-
- The SEARCH response occurs as a result of a SEARCH or UID SEARCH
- command. The number(s) refer to those messages that match the
- search criteria. For SEARCH, these are message sequence numbers;
- for UID SEARCH, these are unique identifiers. Each number is
- delimited by a space.
-
- Example: S: * SEARCH 2 3 6
-
-7.2.6. FLAGS Response
-
- Contents: flag parenthesized list
-
- The FLAGS response occurs as a result of a SELECT or EXAMINE
- command. The flag parenthesized list identifies the flags (at a
- minimum, the system-defined flags) that are applicable for this
- mailbox. Flags other than the system flags can also exist,
- depending on server implementation.
-
- The update from the FLAGS response MUST be recorded by the client.
-
- Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
-
-7.3. Server Responses - Mailbox Size
-
- These responses are always untagged. This is how changes in the size
- of the mailbox are trasnmitted from the server to the client.
- Immediately following the "*" token is a number that represents a
- message count.
-
-7.3.1. EXISTS Response
-
- Contents: none
-
- The EXISTS response reports the number of messages in the mailbox.
- This response occurs as a result of a SELECT or EXAMINE command,
- and if the size of the mailbox changes (e.g. new mail).
-
- The update from the EXISTS response MUST be recorded by the
- client.
-
- Example: S: * 23 EXISTS
-
-
-
-
-
-
-
-
-
-
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-
-
-7.3.2. RECENT Response
-
- Contents: none
-
- The RECENT response reports the number of messages with the
- \Recent flag set. This response occurs as a result of a SELECT or
- EXAMINE command, and if the size of the mailbox changes (e.g. new
- mail).
-
- Note: It is not guaranteed that the message sequence numbers of
- recent messages will be a contiguous range of the highest n
- messages in the mailbox (where n is the value reported by the
- RECENT response). Examples of situations in which this is not
- the case are: multiple clients having the same mailbox open
- (the first session to be notified will see it as recent, others
- will probably see it as non-recent), and when the mailbox is
- re-ordered by a non-IMAP agent.
-
- The only reliable way to identify recent messages is to look at
- message flags to see which have the \Recent flag set, or to do
- a SEARCH RECENT.
-
- The update from the RECENT response MUST be recorded by the
- client.
-
- Example: S: * 5 RECENT
-
-7.4. Server Responses - Message Status
-
- These responses are always untagged. This is how message data are
- transmitted from the server to the client, often as a result of a
- command with the same name. Immediately following the "*" token is a
- number that represents a message sequence number.
-
-7.4.1. EXPUNGE Response
-
- Contents: none
-
- The EXPUNGE response reports that the specified message sequence
- number has been permanently removed from the mailbox. The message
- sequence number for each successive message in the mailbox is
- immediately decremented by 1, and this decrement is reflected in
- message sequence numbers in subsequent responses (including other
- untagged EXPUNGE responses).
-
- As a result of the immediate decrement rule, message sequence
- numbers that appear in a set of successive EXPUNGE responses
- depend upon whether the messages are removed starting from lower
-
-
-
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-
-
- numbers to higher numbers, or from higher numbers to lower
- numbers. For example, if the last 5 messages in a 9-message
- mailbox are expunged; a "lower to higher" server will send five
- untagged EXPUNGE responses for message sequence number 5, whereas
- a "higher to lower server" will send successive untagged EXPUNGE
- responses for message sequence numbers 9, 8, 7, 6, and 5.
-
- An EXPUNGE response MUST NOT be sent when no command is in
- progress; nor while responding to a FETCH, STORE, or SEARCH
- command. This rule is necessary to prevent a loss of
- synchronization of message sequence numbers between client and
- server.
-
- The update from the EXPUNGE response MUST be recorded by the
- client.
-
- Example: S: * 44 EXPUNGE
-
-7.4.2. FETCH Response
-
- Contents: message data
-
- The FETCH response returns data about a message to the client.
- The data are pairs of data item names and their values in
- parentheses. This response occurs as the result of a FETCH or
- STORE command, as well as by unilateral server decision (e.g. flag
- updates).
-
- The current data items are:
-
- BODY A form of BODYSTRUCTURE without extension data.
-
- BODY[<section>]<<origin_octet>>
- A string expressing the body contents of the
- specified section. The string SHOULD be
- interpreted by the client according to the content
- transfer encoding, body type, and subtype.
-
- If the origin octet is specified, this string is a
- substring of the entire body contents, starting at
- that origin octet. This means that BODY[]<0> MAY
- be truncated, but BODY[] is NEVER truncated.
-
- 8-bit textual data is permitted if a [CHARSET]
- identifier is part of the body parameter
- parenthesized list for this section. Note that
- headers (part specifiers HEADER or MIME, or the
- header portion of a MESSAGE/RFC822 part), MUST be
-
-
-
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-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- 7-bit; 8-bit characters are not permitted in
- headers. Note also that the blank line at the end
- of the header is always included in header data.
-
- Non-textual data such as binary data MUST be
- transfer encoded into a textual form such as BASE64
- prior to being sent to the client. To derive the
- original binary data, the client MUST decode the
- transfer encoded string.
-
- BODYSTRUCTURE A parenthesized list that describes the [MIME-IMB]
- body structure of a message. This is computed by
- the server by parsing the [MIME-IMB] header fields,
- defaulting various fields as necessary.
-
- For example, a simple text message of 48 lines and
- 2279 octets can have a body structure of: ("TEXT"
- "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 2279
- 48)
-
- Multiple parts are indicated by parenthesis
- nesting. Instead of a body type as the first
- element of the parenthesized list there is a nested
- body. The second element of the parenthesized list
- is the multipart subtype (mixed, digest, parallel,
- alternative, etc.).
-
- For example, a two part message consisting of a
- text and a BASE645-encoded text attachment can have
- a body structure of: (("TEXT" "PLAIN" ("CHARSET"
- "US-ASCII") NIL NIL "7BIT" 1152 23)("TEXT" "PLAIN"
- ("CHARSET" "US-ASCII" "NAME" "cc.diff")
- "<960723163407.20117h@cac.washington.edu>"
- "Compiler diff" "BASE64" 4554 73) "MIXED"))
-
- Extension data follows the multipart subtype.
- Extension data is never returned with the BODY
- fetch, but can be returned with a BODYSTRUCTURE
- fetch. Extension data, if present, MUST be in the
- defined order.
-
- The extension data of a multipart body part are in
- the following order:
-
- body parameter parenthesized list
- A parenthesized list of attribute/value pairs
- [e.g. ("foo" "bar" "baz" "rag") where "bar" is
- the value of "foo" and "rag" is the value of
-
-
-
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-
-
- "baz"] as defined in [MIME-IMB].
-
- body disposition
- A parenthesized list, consisting of a
- disposition type string followed by a
- parenthesized list of disposition
- attribute/value pairs. The disposition type and
- attribute names will be defined in a future
- standards-track revision to [DISPOSITION].
-
- body language
- A string or parenthesized list giving the body
- language value as defined in [LANGUAGE-TAGS].
-
- Any following extension data are not yet defined in
- this version of the protocol. Such extension data
- can consist of zero or more NILs, strings, numbers,
- or potentially nested parenthesized lists of such
- data. Client implementations that do a
- BODYSTRUCTURE fetch MUST be prepared to accept such
- extension data. Server implementations MUST NOT
- send such extension data until it has been defined
- by a revision of this protocol.
-
- The basic fields of a non-multipart body part are
- in the following order:
-
- body type
- A string giving the content media type name as
- defined in [MIME-IMB].
-
- body subtype
- A string giving the content subtype name as
- defined in [MIME-IMB].
-
- body parameter parenthesized list
- A parenthesized list of attribute/value pairs
- [e.g. ("foo" "bar" "baz" "rag") where "bar" is
- the value of "foo" and "rag" is the value of
- "baz"] as defined in [MIME-IMB].
-
- body id
- A string giving the content id as defined in
- [MIME-IMB].
-
- body description
- A string giving the content description as
- defined in [MIME-IMB].
-
-
-
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-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- body encoding
- A string giving the content transfer encoding as
- defined in [MIME-IMB].
-
- body size
- A number giving the size of the body in octets.
- Note that this size is the size in its transfer
- encoding and not the resulting size after any
- decoding.
-
- A body type of type MESSAGE and subtype RFC822
- contains, immediately after the basic fields, the
- envelope structure, body structure, and size in
- text lines of the encapsulated message.
-
- A body type of type TEXT contains, immediately
- after the basic fields, the size of the body in
- text lines. Note that this size is the size in its
- content transfer encoding and not the resulting
- size after any decoding.
-
- Extension data follows the basic fields and the
- type-specific fields listed above. Extension data
- is never returned with the BODY fetch, but can be
- returned with a BODYSTRUCTURE fetch. Extension
- data, if present, MUST be in the defined order.
-
- The extension data of a non-multipart body part are
- in the following order:
-
- body MD5
- A string giving the body MD5 value as defined in
- [MD5].
-
- body disposition
- A parenthesized list with the same content and
- function as the body disposition for a multipart
- body part.
-
- body language
- A string or parenthesized list giving the body
- language value as defined in [LANGUAGE-TAGS].
-
- Any following extension data are not yet defined in
- this version of the protocol, and would be as
- described above under multipart extension data.
-
-
-
-
-
-Crispin Standards Track [Page 61]
-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- ENVELOPE A parenthesized list that describes the envelope
- structure of a message. This is computed by the
- server by parsing the [RFC-822] header into the
- component parts, defaulting various fields as
- necessary.
-
- The fields of the envelope structure are in the
- following order: date, subject, from, sender,
- reply-to, to, cc, bcc, in-reply-to, and message-id.
- The date, subject, in-reply-to, and message-id
- fields are strings. The from, sender, reply-to,
- to, cc, and bcc fields are parenthesized lists of
- address structures.
-
- An address structure is a parenthesized list that
- describes an electronic mail address. The fields
- of an address structure are in the following order:
- personal name, [SMTP] at-domain-list (source
- route), mailbox name, and host name.
-
- [RFC-822] group syntax is indicated by a special
- form of address structure in which the host name
- field is NIL. If the mailbox name field is also
- NIL, this is an end of group marker (semi-colon in
- RFC 822 syntax). If the mailbox name field is
- non-NIL, this is a start of group marker, and the
- mailbox name field holds the group name phrase.
-
- Any field of an envelope or address structure that
- is not applicable is presented as NIL. Note that
- the server MUST default the reply-to and sender
- fields from the from field; a client is not
- expected to know to do this.
-
- FLAGS A parenthesized list of flags that are set for this
- message.
-
- INTERNALDATE A string representing the internal date of the
- message.
-
- RFC822 Equivalent to BODY[].
-
- RFC822.HEADER Equivalent to BODY.PEEK[HEADER].
-
- RFC822.SIZE A number expressing the [RFC-822] size of the
- message.
-
- RFC822.TEXT Equivalent to BODY[TEXT].
-
-
-
-Crispin Standards Track [Page 62]
-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- UID A number expressing the unique identifier of the
- message.
-
-
- Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827)
-
-7.5. Server Responses - Command Continuation Request
-
- The command continuation request response is indicated by a "+" token
- instead of a tag. This form of response indicates that the server is
- ready to accept the continuation of a command from the client. The
- remainder of this response is a line of text.
-
- This response is used in the AUTHORIZATION command to transmit server
- data to the client, and request additional client data. This
- response is also used if an argument to any command is a literal.
-
- The client is not permitted to send the octets of the literal unless
- the server indicates that it expects it. This permits the server to
- process commands and reject errors on a line-by-line basis. The
- remainder of the command, including the CRLF that terminates a
- command, follows the octets of the literal. If there are any
- additional command arguments the literal octets are followed by a
- space and those arguments.
-
- Example: C: A001 LOGIN {11}
- S: + Ready for additional command text
- C: FRED FOOBAR {7}
- S: + Ready for additional command text
- C: fat man
- S: A001 OK LOGIN completed
- C: A044 BLURDYBLOOP {102856}
- S: A044 BAD No such command as "BLURDYBLOOP"
-
-8. Sample IMAP4rev1 connection
-
- The following is a transcript of an IMAP4rev1 connection. A long
- line in this sample is broken for editorial clarity.
-
-S: * OK IMAP4rev1 Service Ready
-C: a001 login mrc secret
-S: a001 OK LOGIN completed
-C: a002 select inbox
-S: * 18 EXISTS
-S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
-S: * 2 RECENT
-S: * OK [UNSEEN 17] Message 17 is the first unseen message
-S: * OK [UIDVALIDITY 3857529045] UIDs valid
-
-
-
-Crispin Standards Track [Page 63]
-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
-S: a002 OK [READ-WRITE] SELECT completed
-C: a003 fetch 12 full
-S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700"
- RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)"
- "IMAP4rev1 WG mtg summary and minutes"
- (("Terry Gray" NIL "gray" "cac.washington.edu"))
- (("Terry Gray" NIL "gray" "cac.washington.edu"))
- (("Terry Gray" NIL "gray" "cac.washington.edu"))
- ((NIL NIL "imap" "cac.washington.edu"))
- ((NIL NIL "minutes" "CNRI.Reston.VA.US")
- ("John Klensin" NIL "KLENSIN" "INFOODS.MIT.EDU")) NIL NIL
- "<B27397-0100000@cac.washington.edu>")
- BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 92))
-S: a003 OK FETCH completed
-C: a004 fetch 12 body[header]
-S: * 12 FETCH (BODY[HEADER] {350}
-S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT)
-S: From: Terry Gray <gray@cac.washington.edu>
-S: Subject: IMAP4rev1 WG mtg summary and minutes
-S: To: imap@cac.washington.edu
-S: cc: minutes@CNRI.Reston.VA.US, John Klensin <KLENSIN@INFOODS.MIT.EDU>
-S: Message-Id: <B27397-0100000@cac.washington.edu>
-S: MIME-Version: 1.0
-S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
-S:
-S: )
-S: a004 OK FETCH completed
-C: a005 store 12 +flags \deleted
-S: * 12 FETCH (FLAGS (\Seen \Deleted))
-S: a005 OK +FLAGS completed
-C: a006 logout
-S: * BYE IMAP4rev1 server terminating connection
-S: a006 OK LOGOUT completed
-
-9. Formal Syntax
-
- The following syntax specification uses the augmented Backus-Naur
- Form (BNF) notation as specified in [RFC-822] with one exception; the
- delimiter used with the "#" construct is a single space (SPACE) and
- not one or more commas.
-
- In the case of alternative or optional rules in which a later rule
- overlaps an earlier rule, the rule which is listed earlier MUST take
- priority. For example, "\Seen" when parsed as a flag is the \Seen
- flag name and not a flag_extension, even though "\Seen" could be
- parsed as a flag_extension. Some, but not all, instances of this
- rule are noted below.
-
-
-
-
-Crispin Standards Track [Page 64]
-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
- Except as noted otherwise, all alphabetic characters are case-
- insensitive. The use of upper or lower case characters to define
- token strings is for editorial clarity only. Implementations MUST
- accept these strings in a case-insensitive fashion.
-
-address ::= "(" addr_name SPACE addr_adl SPACE addr_mailbox
- SPACE addr_host ")"
-
-addr_adl ::= nstring
- ;; Holds route from [RFC-822] route-addr if
- ;; non-NIL
-
-addr_host ::= nstring
- ;; NIL indicates [RFC-822] group syntax.
- ;; Otherwise, holds [RFC-822] domain name
-
-addr_mailbox ::= nstring
- ;; NIL indicates end of [RFC-822] group; if
- ;; non-NIL and addr_host is NIL, holds
- ;; [RFC-822] group name.
- ;; Otherwise, holds [RFC-822] local-part
-
-addr_name ::= nstring
- ;; Holds phrase from [RFC-822] mailbox if
- ;; non-NIL
-
-alpha ::= "A" / "B" / "C" / "D" / "E" / "F" / "G" / "H" /
- "I" / "J" / "K" / "L" / "M" / "N" / "O" / "P" /
- "Q" / "R" / "S" / "T" / "U" / "V" / "W" / "X" /
- "Y" / "Z" /
- "a" / "b" / "c" / "d" / "e" / "f" / "g" / "h" /
- "i" / "j" / "k" / "l" / "m" / "n" / "o" / "p" /
- "q" / "r" / "s" / "t" / "u" / "v" / "w" / "x" /
- "y" / "z"
- ;; Case-sensitive
-
-append ::= "APPEND" SPACE mailbox [SPACE flag_list]
- [SPACE date_time] SPACE literal
-
-astring ::= atom / string
-
-atom ::= 1*ATOM_CHAR
-
-ATOM_CHAR ::= <any CHAR except atom_specials>
-
-atom_specials ::= "(" / ")" / "{" / SPACE / CTL / list_wildcards /
- quoted_specials
-
-
-
-
-Crispin Standards Track [Page 65]
-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
-authenticate ::= "AUTHENTICATE" SPACE auth_type *(CRLF base64)
-
-auth_type ::= atom
- ;; Defined by [IMAP-AUTH]
-
-base64 ::= *(4base64_char) [base64_terminal]
-
-base64_char ::= alpha / digit / "+" / "/"
-
-base64_terminal ::= (2base64_char "==") / (3base64_char "=")
-
-body ::= "(" body_type_1part / body_type_mpart ")"
-
-body_extension ::= nstring / number / "(" 1#body_extension ")"
- ;; Future expansion. Client implementations
- ;; MUST accept body_extension fields. Server
- ;; implementations MUST NOT generate
- ;; body_extension fields except as defined by
- ;; future standard or standards-track
- ;; revisions of this specification.
-
-body_ext_1part ::= body_fld_md5 [SPACE body_fld_dsp
- [SPACE body_fld_lang
- [SPACE 1#body_extension]]]
- ;; MUST NOT be returned on non-extensible
- ;; "BODY" fetch
-
-body_ext_mpart ::= body_fld_param
- [SPACE body_fld_dsp SPACE body_fld_lang
- [SPACE 1#body_extension]]
- ;; MUST NOT be returned on non-extensible
- ;; "BODY" fetch
-
-body_fields ::= body_fld_param SPACE body_fld_id SPACE
- body_fld_desc SPACE body_fld_enc SPACE
- body_fld_octets
-
-body_fld_desc ::= nstring
-
-body_fld_dsp ::= "(" string SPACE body_fld_param ")" / nil
-
-body_fld_enc ::= (<"> ("7BIT" / "8BIT" / "BINARY" / "BASE64"/
- "QUOTED-PRINTABLE") <">) / string
-
-body_fld_id ::= nstring
-
-body_fld_lang ::= nstring / "(" 1#string ")"
-
-
-
-
-Crispin Standards Track [Page 66]
-\f
-RFC 2060 IMAP4rev1 December 1996
-
-
-body_fld_lines ::= number
-
-body_fld_md5 ::= nstring
-
-body_fld_octets ::= number
-
-body_fld_param ::= "(" 1#(string SPACE string) ")" / nil
-
-body_type_1part ::= (body_type_basic / body_type_msg / body_type_text)
- [SPACE body_ext_1part]
-
-body_type_basic ::= media_basic SPACE body_fields
- ;; MESSAGE subtype MUST NOT be "RFC822"
-
-body_type_mpart ::= 1*body SPACE media_subtype
- [SPACE body_ext_mpart]
-
-body_type_msg ::= media_message SPACE body_fields SPACE envelope
- SPACE body SPACE body_fld_lines
-
-body_type_text ::= media_text SPACE body_fields SPACE body_fld_lines
-
-capability ::= "AUTH=" auth_type / atom
- ;; New capabilities MUST begin with "X" or be
- ;; registered with IANA as standard or
- ;; standards-track
-
-capability_data ::= "CAPABILITY" SPACE [1#capability SPACE] "IMAP4rev1"
- [SPACE 1#capability]
- ;; IMAP4rev1 servers which offer RFC 1730
- ;; compatibility MUST list "IMAP4" as the first
- ;; capability.
-
-CHAR ::= <any 7-bit US-ASCII character except NUL,
- 0x01 - 0x7f>
-
-CHAR8 ::= <any 8-bit octet except NUL, 0x01 - 0xff>
-
-command ::= tag SPACE (command_any / command_auth /
- command_nonauth / command_select) CRLF
- ;; Modal based on state
-
-command_any ::= "CAPABILITY" / "LOGOUT" / "NOOP" / x_command
- ;; Valid in all states
-
-command_auth ::= append / create / delete / examine / list / lsub /
- rename / select / status / subscribe / unsubscribe
- ;; Valid only in Authenticated or Selected state
-
-
-
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-
-
-command_nonauth ::= login / authenticate
- ;; Valid only when in Non-Authenticated state
-
-command_select ::= "CHECK" / "CLOSE" / "EXPUNGE" /
- copy / fetch / store / uid / search
- ;; Valid only when in Selected state
-
-continue_req ::= "+" SPACE (resp_text / base64)
-
-copy ::= "COPY" SPACE set SPACE mailbox
-
-CR ::= <ASCII CR, carriage return, 0x0D>
-
-create ::= "CREATE" SPACE mailbox
- ;; Use of INBOX gives a NO error
-
-CRLF ::= CR LF
-
-CTL ::= <any ASCII control character and DEL,
- 0x00 - 0x1f, 0x7f>
-
-date ::= date_text / <"> date_text <">
-
-date_day ::= 1*2digit
- ;; Day of month
-
-date_day_fixed ::= (SPACE digit) / 2digit
- ;; Fixed-format version of date_day
-
-date_month ::= "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" /
- "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec"
-
-date_text ::= date_day "-" date_month "-" date_year
-
-date_year ::= 4digit
-
-date_time ::= <"> date_day_fixed "-" date_month "-" date_year
- SPACE time SPACE zone <">
-
-delete ::= "DELETE" SPACE mailbox
- ;; Use of INBOX gives a NO error
-
-digit ::= "0" / digit_nz
-
-digit_nz ::= "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" /
- "9"
-
-
-
-
-
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-RFC 2060 IMAP4rev1 December 1996
-
-
-envelope ::= "(" env_date SPACE env_subject SPACE env_from
- SPACE env_sender SPACE env_reply_to SPACE env_to
- SPACE env_cc SPACE env_bcc SPACE env_in_reply_to
- SPACE env_message_id ")"
-
-env_bcc ::= "(" 1*address ")" / nil
-
-env_cc ::= "(" 1*address ")" / nil
-
-env_date ::= nstring
-
-env_from ::= "(" 1*address ")" / nil
-
-env_in_reply_to ::= nstring
-
-env_message_id ::= nstring
-
-env_reply_to ::= "(" 1*address ")" / nil
-
-env_sender ::= "(" 1*address ")" / nil
-
-env_subject ::= nstring
-
-env_to ::= "(" 1*address ")" / nil
-
-examine ::= "EXAMINE" SPACE mailbox
-
-fetch ::= "FETCH" SPACE set SPACE ("ALL" / "FULL" /
- "FAST" / fetch_att / "(" 1#fetch_att ")")
-
-fetch_att ::= "ENVELOPE" / "FLAGS" / "INTERNALDATE" /
- "RFC822" [".HEADER" / ".SIZE" / ".TEXT"] /
- "BODY" ["STRUCTURE"] / "UID" /
- "BODY" [".PEEK"] section
- ["<" number "." nz_number ">"]
-
-flag ::= "\Answered" / "\Flagged" / "\Deleted" /
- "\Seen" / "\Draft" / flag_keyword / flag_extension
-
-flag_extension ::= "\" atom
- ;; Future expansion. Client implementations
- ;; MUST accept flag_extension flags. Server
- ;; implementations MUST NOT generate
- ;; flag_extension flags except as defined by
- ;; future standard or standards-track
- ;; revisions of this specification.
-
-flag_keyword ::= atom
-
-
-
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-
-
-flag_list ::= "(" #flag ")"
-
-greeting ::= "*" SPACE (resp_cond_auth / resp_cond_bye) CRLF
-
-header_fld_name ::= astring
-
-header_list ::= "(" 1#header_fld_name ")"
-
-LF ::= <ASCII LF, line feed, 0x0A>
-
-list ::= "LIST" SPACE mailbox SPACE list_mailbox
-
-list_mailbox ::= 1*(ATOM_CHAR / list_wildcards) / string
-
-list_wildcards ::= "%" / "*"
-
-literal ::= "{" number "}" CRLF *CHAR8
- ;; Number represents the number of CHAR8 octets
-
-login ::= "LOGIN" SPACE userid SPACE password
-
-lsub ::= "LSUB" SPACE mailbox SPACE list_mailbox
-
-mailbox ::= "INBOX" / astring
- ;; INBOX is case-insensitive. All case variants of
- ;; INBOX (e.g. "iNbOx") MUST be interpreted as INBOX
- ;; not as an astring. Refer to section 5.1 for
- ;; further semantic details of mailbox names.
-
-mailbox_data ::= "FLAGS" SPACE flag_list /
- "LIST" SPACE mailbox_list /
- "LSUB" SPACE mailbox_list /
- "MAILBOX" SPACE text /
- "SEARCH" [SPACE 1#nz_number] /
- "STATUS" SPACE mailbox SPACE
- "(" #<status_att number ")" /
- number SPACE "EXISTS" / number SPACE "RECENT"
-
-mailbox_list ::= "(" #("\Marked" / "\Noinferiors" /
- "\Noselect" / "\Unmarked" / flag_extension) ")"
- SPACE (<"> QUOTED_CHAR <"> / nil) SPACE mailbox
-
-media_basic ::= (<"> ("APPLICATION" / "AUDIO" / "IMAGE" /
- "MESSAGE" / "VIDEO") <">) / string)
- SPACE media_subtype
- ;; Defined in [MIME-IMT]
-
-media_message ::= <"> "MESSAGE" <"> SPACE <"> "RFC822" <">
-
-
-
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-
-
- ;; Defined in [MIME-IMT]
-
-media_subtype ::= string
- ;; Defined in [MIME-IMT]
-
-media_text ::= <"> "TEXT" <"> SPACE media_subtype
- ;; Defined in [MIME-IMT]
-
-message_data ::= nz_number SPACE ("EXPUNGE" /
- ("FETCH" SPACE msg_att))
-
-msg_att ::= "(" 1#("ENVELOPE" SPACE envelope /
- "FLAGS" SPACE "(" #(flag / "\Recent") ")" /
- "INTERNALDATE" SPACE date_time /
- "RFC822" [".HEADER" / ".TEXT"] SPACE nstring /
- "RFC822.SIZE" SPACE number /
- "BODY" ["STRUCTURE"] SPACE body /
- "BODY" section ["<" number ">"] SPACE nstring /
- "UID" SPACE uniqueid) ")"
-
-nil ::= "NIL"
-
-nstring ::= string / nil
-
-number ::= 1*digit
- ;; Unsigned 32-bit integer
- ;; (0 <= n < 4,294,967,296)
-
-nz_number ::= digit_nz *digit
- ;; Non-zero unsigned 32-bit integer
- ;; (0 < n < 4,294,967,296)
-
-password ::= astring
-
-quoted ::= <"> *QUOTED_CHAR <">
-
-QUOTED_CHAR ::= <any TEXT_CHAR except quoted_specials> /
- "\" quoted_specials
-
-quoted_specials ::= <"> / "\"
-
-rename ::= "RENAME" SPACE mailbox SPACE mailbox
- ;; Use of INBOX as a destination gives a NO error
-
-response ::= *(continue_req / response_data) response_done
-
-response_data ::= "*" SPACE (resp_cond_state / resp_cond_bye /
- mailbox_data / message_data / capability_data)
-
-
-
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-
-
- CRLF
-
-response_done ::= response_tagged / response_fatal
-
-response_fatal ::= "*" SPACE resp_cond_bye CRLF
- ;; Server closes connection immediately
-
-response_tagged ::= tag SPACE resp_cond_state CRLF
-
-resp_cond_auth ::= ("OK" / "PREAUTH") SPACE resp_text
- ;; Authentication condition
-
-resp_cond_bye ::= "BYE" SPACE resp_text
-
-resp_cond_state ::= ("OK" / "NO" / "BAD") SPACE resp_text
- ;; Status condition
-
-resp_text ::= ["[" resp_text_code "]" SPACE] (text_mime2 / text)
- ;; text SHOULD NOT begin with "[" or "="
-
-resp_text_code ::= "ALERT" / "PARSE" /
- "PERMANENTFLAGS" SPACE "(" #(flag / "\*") ")" /
- "READ-ONLY" / "READ-WRITE" / "TRYCREATE" /
- "UIDVALIDITY" SPACE nz_number /
- "UNSEEN" SPACE nz_number /
- atom [SPACE 1*<any TEXT_CHAR except "]">]
-
-search ::= "SEARCH" SPACE ["CHARSET" SPACE astring SPACE]
- 1#search_key
- ;; [CHARSET] MUST be registered with IANA
-
-search_key ::= "ALL" / "ANSWERED" / "BCC" SPACE astring /
- "BEFORE" SPACE date / "BODY" SPACE astring /
- "CC" SPACE astring / "DELETED" / "FLAGGED" /
- "FROM" SPACE astring /
- "KEYWORD" SPACE flag_keyword / "NEW" / "OLD" /
- "ON" SPACE date / "RECENT" / "SEEN" /
- "SINCE" SPACE date / "SUBJECT" SPACE astring /
- "TEXT" SPACE astring / "TO" SPACE astring /
- "UNANSWERED" / "UNDELETED" / "UNFLAGGED" /
- "UNKEYWORD" SPACE flag_keyword / "UNSEEN" /
- ;; Above this line were in [IMAP2]
- "DRAFT" /
- "HEADER" SPACE header_fld_name SPACE astring /
- "LARGER" SPACE number / "NOT" SPACE search_key /
- "OR" SPACE search_key SPACE search_key /
- "SENTBEFORE" SPACE date / "SENTON" SPACE date /
- "SENTSINCE" SPACE date / "SMALLER" SPACE number /
-
-
-
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-
-
- "UID" SPACE set / "UNDRAFT" / set /
- "(" 1#search_key ")"
-
-section ::= "[" [section_text / (nz_number *["." nz_number]
- ["." (section_text / "MIME")])] "]"
-
-section_text ::= "HEADER" / "HEADER.FIELDS" [".NOT"]
- SPACE header_list / "TEXT"
-
-select ::= "SELECT" SPACE mailbox
-
-sequence_num ::= nz_number / "*"
- ;; * is the largest number in use. For message
- ;; sequence numbers, it is the number of messages
- ;; in the mailbox. For unique identifiers, it is
- ;; the unique identifier of the last message in
- ;; the mailbox.
-
-set ::= sequence_num / (sequence_num ":" sequence_num) /
- (set "," set)
- ;; Identifies a set of messages. For message
- ;; sequence numbers, these are consecutive
- ;; numbers from 1 to the number of messages in
- ;; the mailbox
- ;; Comma delimits individual numbers, colon
- ;; delimits between two numbers inclusive.
- ;; Example: 2,4:7,9,12:* is 2,4,5,6,7,9,12,13,
- ;; 14,15 for a mailbox with 15 messages.
-
-SPACE ::= <ASCII SP, space, 0x20>
-
-status ::= "STATUS" SPACE mailbox SPACE "(" 1#status_att ")"
-
-status_att ::= "MESSAGES" / "RECENT" / "UIDNEXT" / "UIDVALIDITY" /
- "UNSEEN"
-
-store ::= "STORE" SPACE set SPACE store_att_flags
-
-store_att_flags ::= (["+" / "-"] "FLAGS" [".SILENT"]) SPACE
- (flag_list / #flag)
-
-string ::= quoted / literal
-
-subscribe ::= "SUBSCRIBE" SPACE mailbox
-
-tag ::= 1*<any ATOM_CHAR except "+">
-
-text ::= 1*TEXT_CHAR
-
-
-
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-
-
-text_mime2 ::= "=?" <charset> "?" <encoding> "?"
- <encoded-text> "?="
- ;; Syntax defined in [MIME-HDRS]
-
-TEXT_CHAR ::= <any CHAR except CR and LF>
-
-time ::= 2digit ":" 2digit ":" 2digit
- ;; Hours minutes seconds
-
-uid ::= "UID" SPACE (copy / fetch / search / store)
- ;; Unique identifiers used instead of message
- ;; sequence numbers
-
-uniqueid ::= nz_number
- ;; Strictly ascending
-
-unsubscribe ::= "UNSUBSCRIBE" SPACE mailbox
-
-userid ::= astring
-
-x_command ::= "X" atom <experimental command arguments>
-
-zone ::= ("+" / "-") 4digit
- ;; Signed four-digit value of hhmm representing
- ;; hours and minutes west of Greenwich (that is,
- ;; (the amount that the given time differs from
- ;; Universal Time). Subtracting the timezone
- ;; from the given time will give the UT form.
- ;; The Universal Time zone is "+0000".
-
-10. Author's Note
-
- This document is a revision or rewrite of earlier documents, and
- supercedes the protocol specification in those documents: RFC 1730,
- unpublished IMAP2bis.TXT document, RFC 1176, and RFC 1064.
-
-11. Security Considerations
-
- IMAP4rev1 protocol transactions, including electronic mail data, are
- sent in the clear over the network unless privacy protection is
- negotiated in the AUTHENTICATE command.
-
- A server error message for an AUTHENTICATE command which fails due to
- invalid credentials SHOULD NOT detail why the credentials are
- invalid.
-
- Use of the LOGIN command sends passwords in the clear. This can be
- avoided by using the AUTHENTICATE command instead.
-
-
-
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-
-
- A server error message for a failing LOGIN command SHOULD NOT specify
- that the user name, as opposed to the password, is invalid.
-
- Additional security considerations are discussed in the section
- discussing the AUTHENTICATE and LOGIN commands.
-
-12. Author's Address
-
- Mark R. Crispin
- Networks and Distributed Computing
- University of Washington
- 4545 15th Aveneue NE
- Seattle, WA 98105-4527
-
- Phone: (206) 543-5762
-
- EMail: MRC@CAC.Washington.EDU
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Crispin Standards Track [Page 75]
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-RFC 2060 IMAP4rev1 December 1996
-
-
-Appendices
-
-A. References
-
-[ACAP] Myers, J. "ACAP -- Application Configuration Access Protocol",
-Work in Progress.
-
-[CHARSET] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2,
-RFC 1700, USC/Information Sciences Institute, October 1994.
-
-[DISPOSITION] Troost, R., and Dorner, S., "Communicating Presentation
-Information in Internet Messages: The Content-Disposition Header",
-RFC 1806, June 1995.
-
-[IMAP-AUTH] Myers, J., "IMAP4 Authentication Mechanism", RFC 1731.
-Carnegie-Mellon University, December 1994.
-
-[IMAP-COMPAT] Crispin, M., "IMAP4 Compatibility with IMAP2bis", RFC
-2061, University of Washington, November 1996.
-
-[IMAP-DISC] Austein, R., "Synchronization Operations for Disconnected
-IMAP4 Clients", Work in Progress.
-
-[IMAP-HISTORICAL] Crispin, M. "IMAP4 Compatibility with IMAP2 and
-IMAP2bis", RFC 1732, University of Washington, December 1994.
-
-[IMAP-MODEL] Crispin, M., "Distributed Electronic Mail Models in
-IMAP4", RFC 1733, University of Washington, December 1994.
-
-[IMAP-OBSOLETE] Crispin, M., "Internet Message Access Protocol -
-Obsolete Syntax", RFC 2062, University of Washington, November 1996.
-
-[IMAP2] Crispin, M., "Interactive Mail Access Protocol - Version 2",
-RFC 1176, University of Washington, August 1990.
-
-[LANGUAGE-TAGS] Alvestrand, H., "Tags for the Identification of
-Languages", RFC 1766, March 1995.
-
-[MD5] Myers, J., and M. Rose, "The Content-MD5 Header Field", RFC
-1864, October 1995.
-
-[MIME-IMB] Freed, N., and N. Borenstein, "MIME (Multipurpose Internet
-Mail Extensions) Part One: Format of Internet Message Bodies", RFC
-2045, November 1996.
-
-[MIME-IMT] Freed, N., and N. Borenstein, "MIME (Multipurpose
-Internet Mail Extensions) Part Two: Media Types", RFC 2046,
-November 1996.
-
-
-
-Crispin Standards Track [Page 76]
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-RFC 2060 IMAP4rev1 December 1996
-
-
-[MIME-HDRS] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
-Part Three: Message Header Extensions for Non-ASCII Text", RFC
-2047, November 1996.
-
-[RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
-Messages", STD 11, RFC 822, University of Delaware, August 1982.
-
-[SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10,
-RFC 821, USC/Information Sciences Institute, August 1982.
-
-[UTF-7] Goldsmith, D., and Davis, M., "UTF-7: A Mail-Safe
-Transformation Format of Unicode", RFC 1642, July 1994.
-
-B. Changes from RFC 1730
-
-1) The STATUS command has been added.
-
-2) Clarify in the formal syntax that the "#" construct can never
-refer to multiple spaces.
-
-3) Obsolete syntax has been moved to a separate document.
-
-4) The PARTIAL command has been obsoleted.
-
-5) The RFC822.HEADER.LINES, RFC822.HEADER.LINES.NOT, RFC822.PEEK, and
-RFC822.TEXT.PEEK fetch attributes have been obsoleted.
-
-6) The "<" origin "." size ">" suffix for BODY text attributes has
-been added.
-
-7) The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, and TEXT part
-specifiers have been added.
-
-8) Support for Content-Disposition and Content-Language has been
-added.
-
-9) The restriction on fetching nested MULTIPART parts has been
-removed.
-
-10) Body part number 0 has been obsoleted.
-
-11) Server-supported authenticators are now identified by
-capabilities.
-
-
-
-
-
-
-
-
-Crispin Standards Track [Page 77]
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-RFC 2060 IMAP4rev1 December 1996
-
-
-12) The capability that identifies this protocol is now called
-"IMAP4rev1". A server that provides backwards support for RFC 1730
-SHOULD emit the "IMAP4" capability in addition to "IMAP4rev1" in its
-CAPABILITY response. Because RFC-1730 required "IMAP4" to appear as
-the first capability, it MUST listed first in the response.
-
-13) A description of the mailbox name namespace convention has been
-added.
-
-14) A description of the international mailbox name convention has
-been added.
-
-15) The UID-NEXT and UID-VALIDITY status items are now called UIDNEXT
-and UIDVALIDITY. This is a change from the IMAP STATUS
-Work in Progress and not from RFC-1730
-
-16) Add a clarification that a null mailbox name argument to the LIST
-command returns an untagged LIST response with the hierarchy
-delimiter and root of the reference argument.
-
-17) Define terms such as "MUST", "SHOULD", and "MUST NOT".
-
-18) Add a section which defines message attributes and more
-thoroughly details the semantics of message sequence numbers, UIDs,
-and flags.
-
-19) Add a clarification detailing the circumstances when a client may
-send multiple commands without waiting for a response, and the
-circumstances in which ambiguities may result.
-
-20) Add a recommendation on server behavior for DELETE and RENAME
-when inferior hierarchical names of the given name exist.
-
-21) Add a clarification that a mailbox name may not be unilaterally
-unsubscribed by the server, even if that mailbox name no longer
-exists.
-
-22) Add a clarification that LIST should return its results quickly
-without undue delay.
-
-23) Add a clarification that the date_time argument to APPEND sets
-the internal date of the message.
-
-24) Add a clarification on APPEND behavior when the target mailbox is
-the currently selected mailbox.
-
-
-
-
-
-
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-RFC 2060 IMAP4rev1 December 1996
-
-
-25) Add a clarification that external changes to flags should be
-always announced via an untagged FETCH even if the current command is
-a STORE with the ".SILENT" suffix.
-
-26) Add a clarification that COPY appends to the target mailbox.
-
-27) Add the NEWNAME response code.
-
-28) Rewrite the description of the untagged BYE response to clarify
-its semantics.
-
-29) Change the reference for the body MD5 to refer to the proper RFC.
-
-30) Clarify that the formal syntax contains rules which may overlap,
-and that in the event of such an overlap the rule which occurs first
-takes precedence.
-
-31) Correct the definition of body_fld_param.
-
-32) More formal syntax for capability_data.
-
-33) Clarify that any case variant of "INBOX" must be interpreted as
-INBOX.
-
-34) Clarify that the human-readable text in resp_text should not
-begin with "[" or "=".
-
-35) Change MIME references to Draft Standard documents.
-
-36) Clarify \Recent semantics.
-
-37) Additional examples.
-
-C. Key Word Index
-
- +FLAGS <flag list> (store command data item) ............... 45
- +FLAGS.SILENT <flag list> (store command data item) ........ 46
- -FLAGS <flag list> (store command data item) ............... 46
- -FLAGS.SILENT <flag list> (store command data item) ........ 46
- ALERT (response code) ...................................... 50
- ALL (fetch item) ........................................... 41
- ALL (search key) ........................................... 38
- ANSWERED (search key) ...................................... 38
- APPEND (command) ........................................... 34
- AUTHENTICATE (command) ..................................... 20
- BAD (response) ............................................. 52
- BCC <string> (search key) .................................. 38
- BEFORE <date> (search key) ................................. 39
-
-
-
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-
-
- BODY (fetch item) .......................................... 41
- BODY (fetch result) ........................................ 58
- BODY <string> (search key) ................................. 39
- BODY.PEEK[<section>]<<partial>> (fetch item) ............... 44
- BODYSTRUCTURE (fetch item) ................................. 44
- BODYSTRUCTURE (fetch result) ............................... 59
- BODY[<section>]<<origin_octet>> (fetch result) ............. 58
- BODY[<section>]<<partial>> (fetch item) .................... 41
- BYE (response) ............................................. 52
- Body Structure (message attribute) ......................... 11
- CAPABILITY (command) ....................................... 18
- CAPABILITY (response) ...................................... 53
- CC <string> (search key) ................................... 39
- CHECK (command) ............................................ 36
- CLOSE (command) ............................................ 36
- COPY (command) ............................................. 46
- CREATE (command) ........................................... 25
- DELETE (command) ........................................... 26
- DELETED (search key) ....................................... 39
- DRAFT (search key) ......................................... 39
- ENVELOPE (fetch item) ...................................... 44
- ENVELOPE (fetch result) .................................... 62
- EXAMINE (command) .......................................... 24
- EXISTS (response) .......................................... 56
- EXPUNGE (command) .......................................... 37
- EXPUNGE (response) ......................................... 57
- Envelope Structure (message attribute) ..................... 11
- FAST (fetch item) .......................................... 44
- FETCH (command) ............................................ 41
- FETCH (response) ........................................... 58
- FLAGGED (search key) ....................................... 39
- FLAGS (fetch item) ......................................... 44
- FLAGS (fetch result) ....................................... 62
- FLAGS (response) ........................................... 56
- FLAGS <flag list> (store command data item) ................ 45
- FLAGS.SILENT <flag list> (store command data item) ......... 45
- FROM <string> (search key) ................................. 39
- FULL (fetch item) .......................................... 44
- Flags (message attribute) .................................. 9
- HEADER (part specifier) .................................... 41
- HEADER <field-name> <string> (search key) .................. 39
- HEADER.FIELDS <header_list> (part specifier) ............... 41
- HEADER.FIELDS.NOT <header_list> (part specifier) ........... 41
- INTERNALDATE (fetch item) .................................. 44
- INTERNALDATE (fetch result) ................................ 62
- Internal Date (message attribute) .......................... 10
- KEYWORD <flag> (search key) ................................ 39
- Keyword (type of flag) ..................................... 10
-
-
-
-Crispin Standards Track [Page 80]
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-RFC 2060 IMAP4rev1 December 1996
-
-
- LARGER <n> (search key) .................................... 39
- LIST (command) ............................................. 30
- LIST (response) ............................................ 54
- LOGIN (command) ............................................ 22
- LOGOUT (command) ........................................... 20
- LSUB (command) ............................................. 32
- LSUB (response) ............................................ 55
- MAY (specification requirement term) ....................... 5
- MESSAGES (status item) ..................................... 33
- MIME (part specifier) ...................................... 42
- MUST (specification requirement term) ...................... 4
- MUST NOT (specification requirement term) .................. 4
- Message Sequence Number (message attribute) ................ 9
- NEW (search key) ........................................... 39
- NEWNAME (response code) .................................... 50
- NO (response) .............................................. 51
- NOOP (command) ............................................. 19
- NOT <search-key> (search key) .............................. 39
- OK (response) .............................................. 51
- OLD (search key) ........................................... 39
- ON <date> (search key) ..................................... 39
- OPTIONAL (specification requirement term) .................. 5
- OR <search-key1> <search-key2> (search key) ................ 39
- PARSE (response code) ...................................... 50
- PERMANENTFLAGS (response code) ............................. 50
- PREAUTH (response) ......................................... 52
- Permanent Flag (class of flag) ............................. 10
- READ-ONLY (response code) .................................. 50
- READ-WRITE (response code) ................................. 50
- RECENT (response) .......................................... 57
- RECENT (search key) ........................................ 39
- RECENT (status item) ....................................... 33
- RENAME (command) ........................................... 27
- REQUIRED (specification requirement term) .................. 4
- RFC822 (fetch item) ........................................ 44
- RFC822 (fetch result) ...................................... 63
- RFC822.HEADER (fetch item) ................................. 44
- RFC822.HEADER (fetch result) ............................... 62
- RFC822.SIZE (fetch item) ................................... 44
- RFC822.SIZE (fetch result) ................................. 62
- RFC822.TEXT (fetch item) ................................... 44
- RFC822.TEXT (fetch result) ................................. 62
- SEARCH (command) ........................................... 37
- SEARCH (response) .......................................... 55
- SEEN (search key) .......................................... 40
- SELECT (command) ........................................... 23
- SENTBEFORE <date> (search key) ............................. 40
- SENTON <date> (search key) ................................. 40
-
-
-
-Crispin Standards Track [Page 81]
-\f
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-
-
- SENTSINCE <date> (search key) .............................. 40
- SHOULD (specification requirement term) .................... 5
- SHOULD NOT (specification requirement term) ................ 5
- SINCE <date> (search key) .................................. 40
- SMALLER <n> (search key) ................................... 40
- STATUS (command) ........................................... 33
- STATUS (response) .......................................... 55
- STORE (command) ............................................ 45
- SUBJECT <string> (search key) .............................. 40
- SUBSCRIBE (command) ........................................ 29
- Session Flag (class of flag) ............................... 10
- System Flag (type of flag) ................................. 9
- TEXT (part specifier) ...................................... 42
- TEXT <string> (search key) ................................. 40
- TO <string> (search key) ................................... 40
- TRYCREATE (response code) .................................. 51
- UID (command) .............................................. 47
- UID (fetch item) ........................................... 44
- UID (fetch result) ......................................... 63
- UID <message set> (search key) ............................. 40
- UIDNEXT (status item) ...................................... 33
- UIDVALIDITY (response code) ................................ 51
- UIDVALIDITY (status item) .................................. 34
- UNANSWERED (search key) .................................... 40
- UNDELETED (search key) ..................................... 40
- UNDRAFT (search key) ....................................... 40
- UNFLAGGED (search key) ..................................... 40
- UNKEYWORD <flag> (search key) .............................. 40
- UNSEEN (response code) ..................................... 51
- UNSEEN (search key) ........................................ 40
- UNSEEN (status item) ....................................... 34
- UNSUBSCRIBE (command) ...................................... 30
- Unique Identifier (UID) (message attribute) ................ 7
- X<atom> (command) .......................................... 48
- [RFC-822] Size (message attribute) ......................... 11
- \Answered (system flag) .................................... 9
- \Deleted (system flag) ..................................... 9
- \Draft (system flag) ....................................... 9
- \Flagged (system flag) ..................................... 9
- \Marked (mailbox name attribute) ........................... 54
- \Noinferiors (mailbox name attribute) ...................... 54
- \Noselect (mailbox name attribute) ......................... 54
- \Recent (system flag) ...................................... 10
- \Seen (system flag) ........................................ 9
- \Unmarked (mailbox name attribute) ......................... 54
-
-
-
-
-
-
-Crispin Standards Track [Page 82]
-\f
--- /dev/null
+
+
+
+
+
+
+Network Working Group M. Crispin
+Request for Comments: 3501 University of Washington
+Obsoletes: 2060 March 2003
+Category: Standards Track
+
+
+ INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1
+
+Status of this Memo
+
+ This document specifies an Internet standards track protocol for the
+ Internet community, and requests discussion and suggestions for
+ improvements. Please refer to the current edition of the "Internet
+ Official Protocol Standards" (STD 1) for the standardization state
+ and status of this protocol. Distribution of this memo is unlimited.
+
+Copyright Notice
+
+ Copyright (C) The Internet Society (2003). All Rights Reserved.
+
+Abstract
+
+ The Internet Message Access Protocol, Version 4rev1 (IMAP4rev1)
+ allows a client to access and manipulate electronic mail messages on
+ a server. IMAP4rev1 permits manipulation of mailboxes (remote
+ message folders) in a way that is functionally equivalent to local
+ folders. IMAP4rev1 also provides the capability for an offline
+ client to resynchronize with the server.
+
+ IMAP4rev1 includes operations for creating, deleting, and renaming
+ mailboxes, checking for new messages, permanently removing messages,
+ setting and clearing flags, RFC 2822 and RFC 2045 parsing, searching,
+ and selective fetching of message attributes, texts, and portions
+ thereof. Messages in IMAP4rev1 are accessed by the use of numbers.
+ These numbers are either message sequence numbers or unique
+ identifiers.
+
+ IMAP4rev1 supports a single server. A mechanism for accessing
+ configuration information to support multiple IMAP4rev1 servers is
+ discussed in RFC 2244.
+
+ IMAP4rev1 does not specify a means of posting mail; this function is
+ handled by a mail transfer protocol such as RFC 2821.
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 1]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+Table of Contents
+
+ IMAP4rev1 Protocol Specification ................................ 4
+ 1. How to Read This Document ............................... 4
+ 1.1. Organization of This Document ........................... 4
+ 1.2. Conventions Used in This Document ....................... 4
+ 1.3. Special Notes to Implementors ........................... 5
+ 2. Protocol Overview ....................................... 6
+ 2.1. Link Level .............................................. 6
+ 2.2. Commands and Responses .................................. 6
+ 2.2.1. Client Protocol Sender and Server Protocol Receiver ..... 6
+ 2.2.2. Server Protocol Sender and Client Protocol Receiver ..... 7
+ 2.3. Message Attributes ...................................... 8
+ 2.3.1. Message Numbers ......................................... 8
+ 2.3.1.1. Unique Identifier (UID) Message Attribute ....... 8
+ 2.3.1.2. Message Sequence Number Message Attribute ....... 10
+ 2.3.2. Flags Message Attribute ................................. 11
+ 2.3.3. Internal Date Message Attribute ......................... 12
+ 2.3.4. [RFC-2822] Size Message Attribute ....................... 12
+ 2.3.5. Envelope Structure Message Attribute .................... 12
+ 2.3.6. Body Structure Message Attribute ........................ 12
+ 2.4. Message Texts ........................................... 13
+ 3. State and Flow Diagram .................................. 13
+ 3.1. Not Authenticated State ................................. 13
+ 3.2. Authenticated State ..................................... 13
+ 3.3. Selected State .......................................... 13
+ 3.4. Logout State ............................................ 14
+ 4. Data Formats ............................................ 16
+ 4.1. Atom .................................................... 16
+ 4.2. Number .................................................. 16
+ 4.3. String .................................................. 16
+ 4.3.1. 8-bit and Binary Strings ................................ 17
+ 4.4. Parenthesized List ...................................... 17
+ 4.5. NIL ..................................................... 17
+ 5. Operational Considerations .............................. 18
+ 5.1. Mailbox Naming .......................................... 18
+ 5.1.1. Mailbox Hierarchy Naming ................................ 19
+ 5.1.2. Mailbox Namespace Naming Convention ..................... 19
+ 5.1.3. Mailbox International Naming Convention ................. 19
+ 5.2. Mailbox Size and Message Status Updates ................. 21
+ 5.3. Response when no Command in Progress .................... 21
+ 5.4. Autologout Timer ........................................ 22
+ 5.5. Multiple Commands in Progress ........................... 22
+ 6. Client Commands ........................................ 23
+ 6.1. Client Commands - Any State ............................ 24
+ 6.1.1. CAPABILITY Command ..................................... 24
+ 6.1.2. NOOP Command ........................................... 25
+ 6.1.3. LOGOUT Command ......................................... 26
+
+
+
+Crispin Standards Track [Page 2]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ 6.2. Client Commands - Not Authenticated State .............. 26
+ 6.2.1. STARTTLS Command ....................................... 27
+ 6.2.2. AUTHENTICATE Command ................................... 28
+ 6.2.3. LOGIN Command .......................................... 30
+ 6.3. Client Commands - Authenticated State .................. 31
+ 6.3.1. SELECT Command ......................................... 32
+ 6.3.2. EXAMINE Command ........................................ 34
+ 6.3.3. CREATE Command ......................................... 34
+ 6.3.4. DELETE Command ......................................... 35
+ 6.3.5. RENAME Command ......................................... 37
+ 6.3.6. SUBSCRIBE Command ...................................... 39
+ 6.3.7. UNSUBSCRIBE Command .................................... 39
+ 6.3.8. LIST Command ........................................... 40
+ 6.3.9. LSUB Command ........................................... 43
+ 6.3.10. STATUS Command ......................................... 44
+ 6.3.11. APPEND Command ......................................... 46
+ 6.4. Client Commands - Selected State ....................... 47
+ 6.4.1. CHECK Command .......................................... 47
+ 6.4.2. CLOSE Command .......................................... 48
+ 6.4.3. EXPUNGE Command ........................................ 49
+ 6.4.4. SEARCH Command ......................................... 49
+ 6.4.5. FETCH Command .......................................... 54
+ 6.4.6. STORE Command .......................................... 58
+ 6.4.7. COPY Command ........................................... 59
+ 6.4.8. UID Command ............................................ 60
+ 6.5. Client Commands - Experimental/Expansion ............... 62
+ 6.5.1. X<atom> Command ........................................ 62
+ 7. Server Responses ....................................... 62
+ 7.1. Server Responses - Status Responses .................... 63
+ 7.1.1. OK Response ............................................ 65
+ 7.1.2. NO Response ............................................ 66
+ 7.1.3. BAD Response ........................................... 66
+ 7.1.4. PREAUTH Response ....................................... 67
+ 7.1.5. BYE Response ........................................... 67
+ 7.2. Server Responses - Server and Mailbox Status ........... 68
+ 7.2.1. CAPABILITY Response .................................... 68
+ 7.2.2. LIST Response .......................................... 69
+ 7.2.3. LSUB Response .......................................... 70
+ 7.2.4 STATUS Response ........................................ 70
+ 7.2.5. SEARCH Response ........................................ 71
+ 7.2.6. FLAGS Response ......................................... 71
+ 7.3. Server Responses - Mailbox Size ........................ 71
+ 7.3.1. EXISTS Response ........................................ 71
+ 7.3.2. RECENT Response ........................................ 72
+ 7.4. Server Responses - Message Status ...................... 72
+ 7.4.1. EXPUNGE Response ....................................... 72
+ 7.4.2. FETCH Response ......................................... 73
+ 7.5. Server Responses - Command Continuation Request ........ 79
+
+
+
+Crispin Standards Track [Page 3]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ 8. Sample IMAP4rev1 connection ............................ 80
+ 9. Formal Syntax .......................................... 81
+ 10. Author's Note .......................................... 92
+ 11. Security Considerations ................................ 92
+ 11.1. STARTTLS Security Considerations ....................... 92
+ 11.2. Other Security Considerations .......................... 93
+ 12. IANA Considerations .................................... 94
+ Appendices ..................................................... 95
+ A. References ............................................. 95
+ B. Changes from RFC 2060 .................................. 97
+ C. Key Word Index ......................................... 103
+ Author's Address ............................................... 107
+ Full Copyright Statement ....................................... 108
+
+IMAP4rev1 Protocol Specification
+
+1. How to Read This Document
+
+1.1. Organization of This Document
+
+ This document is written from the point of view of the implementor of
+ an IMAP4rev1 client or server. Beyond the protocol overview in
+ section 2, it is not optimized for someone trying to understand the
+ operation of the protocol. The material in sections 3 through 5
+ provides the general context and definitions with which IMAP4rev1
+ operates.
+
+ Sections 6, 7, and 9 describe the IMAP commands, responses, and
+ syntax, respectively. The relationships among these are such that it
+ is almost impossible to understand any of them separately. In
+ particular, do not attempt to deduce command syntax from the command
+ section alone; instead refer to the Formal Syntax section.
+
+1.2. Conventions Used in This Document
+
+ "Conventions" are basic principles or procedures. Document
+ conventions are noted in this section.
+
+ In examples, "C:" and "S:" indicate lines sent by the client and
+ server respectively.
+
+ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+ "SHOULD", "SHOULD NOT", "MAY", and "OPTIONAL" in this document are to
+ be interpreted as described in [KEYWORDS].
+
+ The word "can" (not "may") is used to refer to a possible
+ circumstance or situation, as opposed to an optional facility of the
+ protocol.
+
+
+
+Crispin Standards Track [Page 4]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ "User" is used to refer to a human user, whereas "client" refers to
+ the software being run by the user.
+
+ "Connection" refers to the entire sequence of client/server
+ interaction from the initial establishment of the network connection
+ until its termination.
+
+ "Session" refers to the sequence of client/server interaction from
+ the time that a mailbox is selected (SELECT or EXAMINE command) until
+ the time that selection ends (SELECT or EXAMINE of another mailbox,
+ CLOSE command, or connection termination).
+
+ Characters are 7-bit US-ASCII unless otherwise specified. Other
+ character sets are indicated using a "CHARSET", as described in
+ [MIME-IMT] and defined in [CHARSET]. CHARSETs have important
+ additional semantics in addition to defining character set; refer to
+ these documents for more detail.
+
+ There are several protocol conventions in IMAP. These refer to
+ aspects of the specification which are not strictly part of the IMAP
+ protocol, but reflect generally-accepted practice. Implementations
+ need to be aware of these conventions, and avoid conflicts whether or
+ not they implement the convention. For example, "&" may not be used
+ as a hierarchy delimiter since it conflicts with the Mailbox
+ International Naming Convention, and other uses of "&" in mailbox
+ names are impacted as well.
+
+1.3. Special Notes to Implementors
+
+ Implementors of the IMAP protocol are strongly encouraged to read the
+ IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in
+ conjunction with this document, to help understand the intricacies of
+ this protocol and how best to build an interoperable product.
+
+ IMAP4rev1 is designed to be upwards compatible from the [IMAP2] and
+ unpublished IMAP2bis protocols. IMAP4rev1 is largely compatible with
+ the IMAP4 protocol described in RFC 1730; the exception being in
+ certain facilities added in RFC 1730 that proved problematic and were
+ subsequently removed. In the course of the evolution of IMAP4rev1,
+ some aspects in the earlier protocols have become obsolete. Obsolete
+ commands, responses, and data formats which an IMAP4rev1
+ implementation can encounter when used with an earlier implementation
+ are described in [IMAP-OBSOLETE].
+
+ Other compatibility issues with IMAP2bis, the most common variant of
+ the earlier protocol, are discussed in [IMAP-COMPAT]. A full
+ discussion of compatibility issues with rare (and presumed extinct)
+
+
+
+
+Crispin Standards Track [Page 5]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is
+ primarily of historical interest.
+
+ IMAP was originally developed for the older [RFC-822] standard, and
+ as a consequence several fetch items in IMAP incorporate "RFC822" in
+ their name. With the exception of RFC822.SIZE, there are more modern
+ replacements; for example, the modern version of RFC822.HEADER is
+ BODY.PEEK[HEADER]. In all cases, "RFC822" should be interpreted as a
+ reference to the updated [RFC-2822] standard.
+
+2. Protocol Overview
+
+2.1. Link Level
+
+ The IMAP4rev1 protocol assumes a reliable data stream such as that
+ provided by TCP. When TCP is used, an IMAP4rev1 server listens on
+ port 143.
+
+2.2. Commands and Responses
+
+ An IMAP4rev1 connection consists of the establishment of a
+ client/server network connection, an initial greeting from the
+ server, and client/server interactions. These client/server
+ interactions consist of a client command, server data, and a server
+ completion result response.
+
+ All interactions transmitted by client and server are in the form of
+ lines, that is, strings that end with a CRLF. The protocol receiver
+ of an IMAP4rev1 client or server is either reading a line, or is
+ reading a sequence of octets with a known count followed by a line.
+
+2.2.1. Client Protocol Sender and Server Protocol Receiver
+
+ The client command begins an operation. Each client command is
+ prefixed with an identifier (typically a short alphanumeric string,
+ e.g., A0001, A0002, etc.) called a "tag". A different tag is
+ generated by the client for each command.
+
+ Clients MUST follow the syntax outlined in this specification
+ strictly. It is a syntax error to send a command with missing or
+ extraneous spaces or arguments.
+
+ There are two cases in which a line from the client does not
+ represent a complete command. In one case, a command argument is
+ quoted with an octet count (see the description of literal in String
+ under Data Formats); in the other case, the command arguments require
+ server feedback (see the AUTHENTICATE command). In either case, the
+
+
+
+
+Crispin Standards Track [Page 6]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ server sends a command continuation request response if it is ready
+ for the octets (if appropriate) and the remainder of the command.
+ This response is prefixed with the token "+".
+
+ Note: If instead, the server detected an error in the
+ command, it sends a BAD completion response with a tag
+ matching the command (as described below) to reject the
+ command and prevent the client from sending any more of the
+ command.
+
+ It is also possible for the server to send a completion
+ response for some other command (if multiple commands are
+ in progress), or untagged data. In either case, the
+ command continuation request is still pending; the client
+ takes the appropriate action for the response, and reads
+ another response from the server. In all cases, the client
+ MUST send a complete command (including receiving all
+ command continuation request responses and command
+ continuations for the command) before initiating a new
+ command.
+
+ The protocol receiver of an IMAP4rev1 server reads a command line
+ from the client, parses the command and its arguments, and transmits
+ server data and a server command completion result response.
+
+2.2.2. Server Protocol Sender and Client Protocol Receiver
+
+ Data transmitted by the server to the client and status responses
+ that do not indicate command completion are prefixed with the token
+ "*", and are called untagged responses.
+
+ Server data MAY be sent as a result of a client command, or MAY be
+ sent unilaterally by the server. There is no syntactic difference
+ between server data that resulted from a specific command and server
+ data that were sent unilaterally.
+
+ The server completion result response indicates the success or
+ failure of the operation. It is tagged with the same tag as the
+ client command which began the operation. Thus, if more than one
+ command is in progress, the tag in a server completion response
+ identifies the command to which the response applies. There are
+ three possible server completion responses: OK (indicating success),
+ NO (indicating failure), or BAD (indicating a protocol error such as
+ unrecognized command or command syntax error).
+
+ Servers SHOULD enforce the syntax outlined in this specification
+ strictly. Any client command with a protocol syntax error, including
+ (but not limited to) missing or extraneous spaces or arguments,
+
+
+
+Crispin Standards Track [Page 7]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ SHOULD be rejected, and the client given a BAD server completion
+ response.
+
+ The protocol receiver of an IMAP4rev1 client reads a response line
+ from the server. It then takes action on the response based upon the
+ first token of the response, which can be a tag, a "*", or a "+".
+
+ A client MUST be prepared to accept any server response at all times.
+ This includes server data that was not requested. Server data SHOULD
+ be recorded, so that the client can reference its recorded copy
+ rather than sending a command to the server to request the data. In
+ the case of certain server data, the data MUST be recorded.
+
+ This topic is discussed in greater detail in the Server Responses
+ section.
+
+2.3. Message Attributes
+
+ In addition to message text, each message has several attributes
+ associated with it. These attributes can be retrieved individually
+ or in conjunction with other attributes or message texts.
+
+2.3.1. Message Numbers
+
+ Messages in IMAP4rev1 are accessed by one of two numbers; the unique
+ identifier or the message sequence number.
+
+
+2.3.1.1. Unique Identifier (UID) Message Attribute
+
+ A 32-bit value assigned to each message, which when used with the
+ unique identifier validity value (see below) forms a 64-bit value
+ that MUST NOT refer to any other message in the mailbox or any
+ subsequent mailbox with the same name forever. Unique identifiers
+ are assigned in a strictly ascending fashion in the mailbox; as each
+ message is added to the mailbox it is assigned a higher UID than the
+ message(s) which were added previously. Unlike message sequence
+ numbers, unique identifiers are not necessarily contiguous.
+
+ The unique identifier of a message MUST NOT change during the
+ session, and SHOULD NOT change between sessions. Any change of
+ unique identifiers between sessions MUST be detectable using the
+ UIDVALIDITY mechanism discussed below. Persistent unique identifiers
+ are required for a client to resynchronize its state from a previous
+ session with the server (e.g., disconnected or offline access
+ clients); this is discussed further in [IMAP-DISC].
+
+
+
+
+
+Crispin Standards Track [Page 8]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Associated with every mailbox are two values which aid in unique
+ identifier handling: the next unique identifier value and the unique
+ identifier validity value.
+
+ The next unique identifier value is the predicted value that will be
+ assigned to a new message in the mailbox. Unless the unique
+ identifier validity also changes (see below), the next unique
+ identifier value MUST have the following two characteristics. First,
+ the next unique identifier value MUST NOT change unless new messages
+ are added to the mailbox; and second, the next unique identifier
+ value MUST change whenever new messages are added to the mailbox,
+ even if those new messages are subsequently expunged.
+
+ Note: The next unique identifier value is intended to
+ provide a means for a client to determine whether any
+ messages have been delivered to the mailbox since the
+ previous time it checked this value. It is not intended to
+ provide any guarantee that any message will have this
+ unique identifier. A client can only assume, at the time
+ that it obtains the next unique identifier value, that
+ messages arriving after that time will have a UID greater
+ than or equal to that value.
+
+ The unique identifier validity value is sent in a UIDVALIDITY
+ response code in an OK untagged response at mailbox selection time.
+ If unique identifiers from an earlier session fail to persist in this
+ session, the unique identifier validity value MUST be greater than
+ the one used in the earlier session.
+
+ Note: Ideally, unique identifiers SHOULD persist at all
+ times. Although this specification recognizes that failure
+ to persist can be unavoidable in certain server
+ environments, it STRONGLY ENCOURAGES message store
+ implementation techniques that avoid this problem. For
+ example:
+
+ 1) Unique identifiers MUST be strictly ascending in the
+ mailbox at all times. If the physical message store is
+ re-ordered by a non-IMAP agent, this requires that the
+ unique identifiers in the mailbox be regenerated, since
+ the former unique identifiers are no longer strictly
+ ascending as a result of the re-ordering.
+
+ 2) If the message store has no mechanism to store unique
+ identifiers, it must regenerate unique identifiers at
+ each session, and each session must have a unique
+ UIDVALIDITY value.
+
+
+
+
+Crispin Standards Track [Page 9]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ 3) If the mailbox is deleted and a new mailbox with the
+ same name is created at a later date, the server must
+ either keep track of unique identifiers from the
+ previous instance of the mailbox, or it must assign a
+ new UIDVALIDITY value to the new instance of the
+ mailbox. A good UIDVALIDITY value to use in this case
+ is a 32-bit representation of the creation date/time of
+ the mailbox. It is alright to use a constant such as
+ 1, but only if it guaranteed that unique identifiers
+ will never be reused, even in the case of a mailbox
+ being deleted (or renamed) and a new mailbox by the
+ same name created at some future time.
+
+ 4) The combination of mailbox name, UIDVALIDITY, and UID
+ must refer to a single immutable message on that server
+ forever. In particular, the internal date, [RFC-2822]
+ size, envelope, body structure, and message texts
+ (RFC822, RFC822.HEADER, RFC822.TEXT, and all BODY[...]
+ fetch data items) must never change. This does not
+ include message numbers, nor does it include attributes
+ that can be set by a STORE command (e.g., FLAGS).
+
+
+2.3.1.2. Message Sequence Number Message Attribute
+
+ A relative position from 1 to the number of messages in the mailbox.
+ This position MUST be ordered by ascending unique identifier. As
+ each new message is added, it is assigned a message sequence number
+ that is 1 higher than the number of messages in the mailbox before
+ that new message was added.
+
+ Message sequence numbers can be reassigned during the session. For
+ example, when a message is permanently removed (expunged) from the
+ mailbox, the message sequence number for all subsequent messages is
+ decremented. The number of messages in the mailbox is also
+ decremented. Similarly, a new message can be assigned a message
+ sequence number that was once held by some other message prior to an
+ expunge.
+
+ In addition to accessing messages by relative position in the
+ mailbox, message sequence numbers can be used in mathematical
+ calculations. For example, if an untagged "11 EXISTS" is received,
+ and previously an untagged "8 EXISTS" was received, three new
+ messages have arrived with message sequence numbers of 9, 10, and 11.
+ Another example, if message 287 in a 523 message mailbox has UID
+ 12345, there are exactly 286 messages which have lesser UIDs and 236
+ messages which have greater UIDs.
+
+
+
+
+Crispin Standards Track [Page 10]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+2.3.2. Flags Message Attribute
+
+ A list of zero or more named tokens associated with the message. A
+ flag is set by its addition to this list, and is cleared by its
+ removal. There are two types of flags in IMAP4rev1. A flag of
+ either type can be permanent or session-only.
+
+ A system flag is a flag name that is pre-defined in this
+ specification. All system flags begin with "\". Certain system
+ flags (\Deleted and \Seen) have special semantics described
+ elsewhere. The currently-defined system flags are:
+
+ \Seen
+ Message has been read
+
+ \Answered
+ Message has been answered
+
+ \Flagged
+ Message is "flagged" for urgent/special attention
+
+ \Deleted
+ Message is "deleted" for removal by later EXPUNGE
+
+ \Draft
+ Message has not completed composition (marked as a draft).
+
+ \Recent
+ Message is "recently" arrived in this mailbox. This session
+ is the first session to have been notified about this
+ message; if the session is read-write, subsequent sessions
+ will not see \Recent set for this message. This flag can not
+ be altered by the client.
+
+ If it is not possible to determine whether or not this
+ session is the first session to be notified about a message,
+ then that message SHOULD be considered recent.
+
+ If multiple connections have the same mailbox selected
+ simultaneously, it is undefined which of these connections
+ will see newly-arrived messages with \Recent set and which
+ will see it without \Recent set.
+
+ A keyword is defined by the server implementation. Keywords do not
+ begin with "\". Servers MAY permit the client to define new keywords
+ in the mailbox (see the description of the PERMANENTFLAGS response
+ code for more information).
+
+
+
+
+Crispin Standards Track [Page 11]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ A flag can be permanent or session-only on a per-flag basis.
+ Permanent flags are those which the client can add or remove from the
+ message flags permanently; that is, concurrent and subsequent
+ sessions will see any change in permanent flags. Changes to session
+ flags are valid only in that session.
+
+ Note: The \Recent system flag is a special case of a
+ session flag. \Recent can not be used as an argument in a
+ STORE or APPEND command, and thus can not be changed at
+ all.
+
+2.3.3. Internal Date Message Attribute
+
+ The internal date and time of the message on the server. This
+ is not the date and time in the [RFC-2822] header, but rather a
+ date and time which reflects when the message was received. In
+ the case of messages delivered via [SMTP], this SHOULD be the
+ date and time of final delivery of the message as defined by
+ [SMTP]. In the case of messages delivered by the IMAP4rev1 COPY
+ command, this SHOULD be the internal date and time of the source
+ message. In the case of messages delivered by the IMAP4rev1
+ APPEND command, this SHOULD be the date and time as specified in
+ the APPEND command description. All other cases are
+ implementation defined.
+
+2.3.4. [RFC-2822] Size Message Attribute
+
+ The number of octets in the message, as expressed in [RFC-2822]
+ format.
+
+2.3.5. Envelope Structure Message Attribute
+
+ A parsed representation of the [RFC-2822] header of the message.
+ Note that the IMAP Envelope structure is not the same as an
+ [SMTP] envelope.
+
+2.3.6. Body Structure Message Attribute
+
+ A parsed representation of the [MIME-IMB] body structure
+ information of the message.
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 12]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+2.4. Message Texts
+
+ In addition to being able to fetch the full [RFC-2822] text of a
+ message, IMAP4rev1 permits the fetching of portions of the full
+ message text. Specifically, it is possible to fetch the
+ [RFC-2822] message header, [RFC-2822] message body, a [MIME-IMB]
+ body part, or a [MIME-IMB] header.
+
+3. State and Flow Diagram
+
+ Once the connection between client and server is established, an
+ IMAP4rev1 connection is in one of four states. The initial
+ state is identified in the server greeting. Most commands are
+ only valid in certain states. It is a protocol error for the
+ client to attempt a command while the connection is in an
+ inappropriate state, and the server will respond with a BAD or
+ NO (depending upon server implementation) command completion
+ result.
+
+3.1. Not Authenticated State
+
+ In the not authenticated state, the client MUST supply
+ authentication credentials before most commands will be
+ permitted. This state is entered when a connection starts
+ unless the connection has been pre-authenticated.
+
+3.2. Authenticated State
+
+ In the authenticated state, the client is authenticated and MUST
+ select a mailbox to access before commands that affect messages
+ will be permitted. This state is entered when a
+ pre-authenticated connection starts, when acceptable
+ authentication credentials have been provided, after an error in
+ selecting a mailbox, or after a successful CLOSE command.
+
+3.3. Selected State
+
+ In a selected state, a mailbox has been selected to access.
+ This state is entered when a mailbox has been successfully
+ selected.
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 13]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+3.4. Logout State
+
+ In the logout state, the connection is being terminated. This
+ state can be entered as a result of a client request (via the
+ LOGOUT command) or by unilateral action on the part of either
+ the client or server.
+
+ If the client requests the logout state, the server MUST send an
+ untagged BYE response and a tagged OK response to the LOGOUT
+ command before the server closes the connection; and the client
+ MUST read the tagged OK response to the LOGOUT command before
+ the client closes the connection.
+
+ A server MUST NOT unilaterally close the connection without
+ sending an untagged BYE response that contains the reason for
+ having done so. A client SHOULD NOT unilaterally close the
+ connection, and instead SHOULD issue a LOGOUT command. If the
+ server detects that the client has unilaterally closed the
+ connection, the server MAY omit the untagged BYE response and
+ simply close its connection.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 14]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ +----------------------+
+ |connection established|
+ +----------------------+
+ ||
+ \/
+ +--------------------------------------+
+ | server greeting |
+ +--------------------------------------+
+ || (1) || (2) || (3)
+ \/ || ||
+ +-----------------+ || ||
+ |Not Authenticated| || ||
+ +-----------------+ || ||
+ || (7) || (4) || ||
+ || \/ \/ ||
+ || +----------------+ ||
+ || | Authenticated |<=++ ||
+ || +----------------+ || ||
+ || || (7) || (5) || (6) ||
+ || || \/ || ||
+ || || +--------+ || ||
+ || || |Selected|==++ ||
+ || || +--------+ ||
+ || || || (7) ||
+ \/ \/ \/ \/
+ +--------------------------------------+
+ | Logout |
+ +--------------------------------------+
+ ||
+ \/
+ +-------------------------------+
+ |both sides close the connection|
+ +-------------------------------+
+
+ (1) connection without pre-authentication (OK greeting)
+ (2) pre-authenticated connection (PREAUTH greeting)
+ (3) rejected connection (BYE greeting)
+ (4) successful LOGIN or AUTHENTICATE command
+ (5) successful SELECT or EXAMINE command
+ (6) CLOSE command, or failed SELECT or EXAMINE command
+ (7) LOGOUT command, server shutdown, or connection closed
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 15]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+4. Data Formats
+
+ IMAP4rev1 uses textual commands and responses. Data in
+ IMAP4rev1 can be in one of several forms: atom, number, string,
+ parenthesized list, or NIL. Note that a particular data item
+ may take more than one form; for example, a data item defined as
+ using "astring" syntax may be either an atom or a string.
+
+4.1. Atom
+
+ An atom consists of one or more non-special characters.
+
+4.2. Number
+
+ A number consists of one or more digit characters, and
+ represents a numeric value.
+
+4.3. String
+
+ A string is in one of two forms: either literal or quoted
+ string. The literal form is the general form of string. The
+ quoted string form is an alternative that avoids the overhead of
+ processing a literal at the cost of limitations of characters
+ which may be used.
+
+ A literal is a sequence of zero or more octets (including CR and
+ LF), prefix-quoted with an octet count in the form of an open
+ brace ("{"), the number of octets, close brace ("}"), and CRLF.
+ In the case of literals transmitted from server to client, the
+ CRLF is immediately followed by the octet data. In the case of
+ literals transmitted from client to server, the client MUST wait
+ to receive a command continuation request (described later in
+ this document) before sending the octet data (and the remainder
+ of the command).
+
+ A quoted string is a sequence of zero or more 7-bit characters,
+ excluding CR and LF, with double quote (<">) characters at each
+ end.
+
+ The empty string is represented as either "" (a quoted string
+ with zero characters between double quotes) or as {0} followed
+ by CRLF (a literal with an octet count of 0).
+
+ Note: Even if the octet count is 0, a client transmitting a
+ literal MUST wait to receive a command continuation request.
+
+
+
+
+
+
+Crispin Standards Track [Page 16]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+4.3.1. 8-bit and Binary Strings
+
+ 8-bit textual and binary mail is supported through the use of a
+ [MIME-IMB] content transfer encoding. IMAP4rev1 implementations MAY
+ transmit 8-bit or multi-octet characters in literals, but SHOULD do
+ so only when the [CHARSET] is identified.
+
+ Although a BINARY body encoding is defined, unencoded binary strings
+ are not permitted. A "binary string" is any string with NUL
+ characters. Implementations MUST encode binary data into a textual
+ form, such as BASE64, before transmitting the data. A string with an
+ excessive amount of CTL characters MAY also be considered to be
+ binary.
+
+4.4. Parenthesized List
+
+ Data structures are represented as a "parenthesized list"; a sequence
+ of data items, delimited by space, and bounded at each end by
+ parentheses. A parenthesized list can contain other parenthesized
+ lists, using multiple levels of parentheses to indicate nesting.
+
+ The empty list is represented as () -- a parenthesized list with no
+ members.
+
+4.5. NIL
+
+ The special form "NIL" represents the non-existence of a particular
+ data item that is represented as a string or parenthesized list, as
+ distinct from the empty string "" or the empty parenthesized list ().
+
+ Note: NIL is never used for any data item which takes the
+ form of an atom. For example, a mailbox name of "NIL" is a
+ mailbox named NIL as opposed to a non-existent mailbox
+ name. This is because mailbox uses "astring" syntax which
+ is an atom or a string. Conversely, an addr-name of NIL is
+ a non-existent personal name, because addr-name uses
+ "nstring" syntax which is NIL or a string, but never an
+ atom.
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 17]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+5. Operational Considerations
+
+ The following rules are listed here to ensure that all IMAP4rev1
+ implementations interoperate properly.
+
+5.1. Mailbox Naming
+
+ Mailbox names are 7-bit. Client implementations MUST NOT attempt to
+ create 8-bit mailbox names, and SHOULD interpret any 8-bit mailbox
+ names returned by LIST or LSUB as UTF-8. Server implementations
+ SHOULD prohibit the creation of 8-bit mailbox names, and SHOULD NOT
+ return 8-bit mailbox names in LIST or LSUB. See section 5.1.3 for
+ more information on how to represent non-ASCII mailbox names.
+
+ Note: 8-bit mailbox names were undefined in earlier
+ versions of this protocol. Some sites used a local 8-bit
+ character set to represent non-ASCII mailbox names. Such
+ usage is not interoperable, and is now formally deprecated.
+
+ The case-insensitive mailbox name INBOX is a special name reserved to
+ mean "the primary mailbox for this user on this server". The
+ interpretation of all other names is implementation-dependent.
+
+ In particular, this specification takes no position on case
+ sensitivity in non-INBOX mailbox names. Some server implementations
+ are fully case-sensitive; others preserve case of a newly-created
+ name but otherwise are case-insensitive; and yet others coerce names
+ to a particular case. Client implementations MUST interact with any
+ of these. If a server implementation interprets non-INBOX mailbox
+ names as case-insensitive, it MUST treat names using the
+ international naming convention specially as described in section
+ 5.1.3.
+
+ There are certain client considerations when creating a new mailbox
+ name:
+
+ 1) Any character which is one of the atom-specials (see the Formal
+ Syntax) will require that the mailbox name be represented as a
+ quoted string or literal.
+
+ 2) CTL and other non-graphic characters are difficult to represent
+ in a user interface and are best avoided.
+
+ 3) Although the list-wildcard characters ("%" and "*") are valid
+ in a mailbox name, it is difficult to use such mailbox names
+ with the LIST and LSUB commands due to the conflict with
+ wildcard interpretation.
+
+
+
+
+Crispin Standards Track [Page 18]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ 4) Usually, a character (determined by the server implementation)
+ is reserved to delimit levels of hierarchy.
+
+ 5) Two characters, "#" and "&", have meanings by convention, and
+ should be avoided except when used in that convention.
+
+5.1.1. Mailbox Hierarchy Naming
+
+ If it is desired to export hierarchical mailbox names, mailbox names
+ MUST be left-to-right hierarchical using a single character to
+ separate levels of hierarchy. The same hierarchy separator character
+ is used for all levels of hierarchy within a single name.
+
+5.1.2. Mailbox Namespace Naming Convention
+
+ By convention, the first hierarchical element of any mailbox name
+ which begins with "#" identifies the "namespace" of the remainder of
+ the name. This makes it possible to disambiguate between different
+ types of mailbox stores, each of which have their own namespaces.
+
+ For example, implementations which offer access to USENET
+ newsgroups MAY use the "#news" namespace to partition the
+ USENET newsgroup namespace from that of other mailboxes.
+ Thus, the comp.mail.misc newsgroup would have a mailbox
+ name of "#news.comp.mail.misc", and the name
+ "comp.mail.misc" can refer to a different object (e.g., a
+ user's private mailbox).
+
+5.1.3. Mailbox International Naming Convention
+
+ By convention, international mailbox names in IMAP4rev1 are specified
+ using a modified version of the UTF-7 encoding described in [UTF-7].
+ Modified UTF-7 may also be usable in servers that implement an
+ earlier version of this protocol.
+
+ In modified UTF-7, printable US-ASCII characters, except for "&",
+ represent themselves; that is, characters with octet values 0x20-0x25
+ and 0x27-0x7e. The character "&" (0x26) is represented by the
+ two-octet sequence "&-".
+
+ All other characters (octet values 0x00-0x1f and 0x7f-0xff) are
+ represented in modified BASE64, with a further modification from
+ [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be
+ used to represent any printing US-ASCII character which can represent
+ itself.
+
+
+
+
+
+
+Crispin Standards Track [Page 19]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ "&" is used to shift to modified BASE64 and "-" to shift back to
+ US-ASCII. There is no implicit shift from BASE64 to US-ASCII, and
+ null shifts ("-&" while in BASE64; note that "&-" while in US-ASCII
+ means "&") are not permitted. However, all names start in US-ASCII,
+ and MUST end in US-ASCII; that is, a name that ends with a non-ASCII
+ ISO-10646 character MUST end with a "-").
+
+ The purpose of these modifications is to correct the following
+ problems with UTF-7:
+
+ 1) UTF-7 uses the "+" character for shifting; this conflicts with
+ the common use of "+" in mailbox names, in particular USENET
+ newsgroup names.
+
+ 2) UTF-7's encoding is BASE64 which uses the "/" character; this
+ conflicts with the use of "/" as a popular hierarchy delimiter.
+
+ 3) UTF-7 prohibits the unencoded usage of "\"; this conflicts with
+ the use of "\" as a popular hierarchy delimiter.
+
+ 4) UTF-7 prohibits the unencoded usage of "~"; this conflicts with
+ the use of "~" in some servers as a home directory indicator.
+
+ 5) UTF-7 permits multiple alternate forms to represent the same
+ string; in particular, printable US-ASCII characters can be
+ represented in encoded form.
+
+ Although modified UTF-7 is a convention, it establishes certain
+ requirements on server handling of any mailbox name with an
+ embedded "&" character. In particular, server implementations
+ MUST preserve the exact form of the modified BASE64 portion of a
+ modified UTF-7 name and treat that text as case-sensitive, even if
+ names are otherwise case-insensitive or case-folded.
+
+ Server implementations SHOULD verify that any mailbox name with an
+ embedded "&" character, used as an argument to CREATE, is: in the
+ correctly modified UTF-7 syntax, has no superfluous shifts, and
+ has no encoding in modified BASE64 of any printing US-ASCII
+ character which can represent itself. However, client
+ implementations MUST NOT depend upon the server doing this, and
+ SHOULD NOT attempt to create a mailbox name with an embedded "&"
+ character unless it complies with the modified UTF-7 syntax.
+
+ Server implementations which export a mail store that does not
+ follow the modified UTF-7 convention MUST convert to modified
+ UTF-7 any mailbox name that contains either non-ASCII characters
+ or the "&" character.
+
+
+
+
+Crispin Standards Track [Page 20]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ For example, here is a mailbox name which mixes English,
+ Chinese, and Japanese text:
+ ~peter/mail/&U,BTFw-/&ZeVnLIqe-
+
+ For example, the string "&Jjo!" is not a valid mailbox
+ name because it does not contain a shift to US-ASCII
+ before the "!". The correct form is "&Jjo-!". The
+ string "&U,BTFw-&ZeVnLIqe-" is not permitted because it
+ contains a superfluous shift. The correct form is
+ "&U,BTF2XlZyyKng-".
+
+5.2. Mailbox Size and Message Status Updates
+
+ At any time, a server can send data that the client did not request.
+ Sometimes, such behavior is REQUIRED. For example, agents other than
+ the server MAY add messages to the mailbox (e.g., new message
+ delivery), change the flags of the messages in the mailbox (e.g.,
+ simultaneous access to the same mailbox by multiple agents), or even
+ remove messages from the mailbox. A server MUST send mailbox size
+ updates automatically if a mailbox size change is observed during the
+ processing of a command. A server SHOULD send message flag updates
+ automatically, without requiring the client to request such updates
+ explicitly.
+
+ Special rules exist for server notification of a client about the
+ removal of messages to prevent synchronization errors; see the
+ description of the EXPUNGE response for more detail. In particular,
+ it is NOT permitted to send an EXISTS response that would reduce the
+ number of messages in the mailbox; only the EXPUNGE response can do
+ this.
+
+ Regardless of what implementation decisions a client makes on
+ remembering data from the server, a client implementation MUST record
+ mailbox size updates. It MUST NOT assume that any command after the
+ initial mailbox selection will return the size of the mailbox.
+
+5.3. Response when no Command in Progress
+
+ Server implementations are permitted to send an untagged response
+ (except for EXPUNGE) while there is no command in progress. Server
+ implementations that send such responses MUST deal with flow control
+ considerations. Specifically, they MUST either (1) verify that the
+ size of the data does not exceed the underlying transport's available
+ window size, or (2) use non-blocking writes.
+
+
+
+
+
+
+
+Crispin Standards Track [Page 21]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+5.4. Autologout Timer
+
+ If a server has an inactivity autologout timer, the duration of that
+ timer MUST be at least 30 minutes. The receipt of ANY command from
+ the client during that interval SHOULD suffice to reset the
+ autologout timer.
+
+5.5. Multiple Commands in Progress
+
+ The client MAY send another command without waiting for the
+ completion result response of a command, subject to ambiguity rules
+ (see below) and flow control constraints on the underlying data
+ stream. Similarly, a server MAY begin processing another command
+ before processing the current command to completion, subject to
+ ambiguity rules. However, any command continuation request responses
+ and command continuations MUST be negotiated before any subsequent
+ command is initiated.
+
+ The exception is if an ambiguity would result because of a command
+ that would affect the results of other commands. Clients MUST NOT
+ send multiple commands without waiting if an ambiguity would result.
+ If the server detects a possible ambiguity, it MUST execute commands
+ to completion in the order given by the client.
+
+ The most obvious example of ambiguity is when a command would affect
+ the results of another command, e.g., a FETCH of a message's flags
+ and a STORE of that same message's flags.
+
+ A non-obvious ambiguity occurs with commands that permit an untagged
+ EXPUNGE response (commands other than FETCH, STORE, and SEARCH),
+ since an untagged EXPUNGE response can invalidate sequence numbers in
+ a subsequent command. This is not a problem for FETCH, STORE, or
+ SEARCH commands because servers are prohibited from sending EXPUNGE
+ responses while any of those commands are in progress. Therefore, if
+ the client sends any command other than FETCH, STORE, or SEARCH, it
+ MUST wait for the completion result response before sending a command
+ with message sequence numbers.
+
+ Note: UID FETCH, UID STORE, and UID SEARCH are different
+ commands from FETCH, STORE, and SEARCH. If the client
+ sends a UID command, it must wait for a completion result
+ response before sending a command with message sequence
+ numbers.
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 22]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ For example, the following non-waiting command sequences are invalid:
+
+ FETCH + NOOP + STORE
+ STORE + COPY + FETCH
+ COPY + COPY
+ CHECK + FETCH
+
+ The following are examples of valid non-waiting command sequences:
+
+ FETCH + STORE + SEARCH + CHECK
+ STORE + COPY + EXPUNGE
+
+ UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting
+ command sequence, depending upon whether or not the second UID
+ SEARCH contains message sequence numbers.
+
+6. Client Commands
+
+ IMAP4rev1 commands are described in this section. Commands are
+ organized by the state in which the command is permitted. Commands
+ which are permitted in multiple states are listed in the minimum
+ permitted state (for example, commands valid in authenticated and
+ selected state are listed in the authenticated state commands).
+
+ Command arguments, identified by "Arguments:" in the command
+ descriptions below, are described by function, not by syntax. The
+ precise syntax of command arguments is described in the Formal Syntax
+ section.
+
+ Some commands cause specific server responses to be returned; these
+ are identified by "Responses:" in the command descriptions below.
+ See the response descriptions in the Responses section for
+ information on these responses, and the Formal Syntax section for the
+ precise syntax of these responses. It is possible for server data to
+ be transmitted as a result of any command. Thus, commands that do
+ not specifically require server data specify "no specific responses
+ for this command" instead of "none".
+
+ The "Result:" in the command description refers to the possible
+ tagged status responses to a command, and any special interpretation
+ of these status responses.
+
+ The state of a connection is only changed by successful commands
+ which are documented as changing state. A rejected command (BAD
+ response) never changes the state of the connection or of the
+ selected mailbox. A failed command (NO response) generally does not
+ change the state of the connection or of the selected mailbox; the
+ exception being the SELECT and EXAMINE commands.
+
+
+
+Crispin Standards Track [Page 23]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.1. Client Commands - Any State
+
+ The following commands are valid in any state: CAPABILITY, NOOP, and
+ LOGOUT.
+
+6.1.1. CAPABILITY Command
+
+ Arguments: none
+
+ Responses: REQUIRED untagged response: CAPABILITY
+
+ Result: OK - capability completed
+ BAD - command unknown or arguments invalid
+
+ The CAPABILITY command requests a listing of capabilities that the
+ server supports. The server MUST send a single untagged
+ CAPABILITY response with "IMAP4rev1" as one of the listed
+ capabilities before the (tagged) OK response.
+
+ A capability name which begins with "AUTH=" indicates that the
+ server supports that particular authentication mechanism. All
+ such names are, by definition, part of this specification. For
+ example, the authorization capability for an experimental
+ "blurdybloop" authenticator would be "AUTH=XBLURDYBLOOP" and not
+ "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP".
+
+ Other capability names refer to extensions, revisions, or
+ amendments to this specification. See the documentation of the
+ CAPABILITY response for additional information. No capabilities,
+ beyond the base IMAP4rev1 set defined in this specification, are
+ enabled without explicit client action to invoke the capability.
+
+ Client and server implementations MUST implement the STARTTLS,
+ LOGINDISABLED, and AUTH=PLAIN (described in [IMAP-TLS])
+ capabilities. See the Security Considerations section for
+ important information.
+
+ See the section entitled "Client Commands -
+ Experimental/Expansion" for information about the form of site or
+ implementation-specific capabilities.
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 24]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Example: C: abcd CAPABILITY
+ S: * CAPABILITY IMAP4rev1 STARTTLS AUTH=GSSAPI
+ LOGINDISABLED
+ S: abcd OK CAPABILITY completed
+ C: efgh STARTTLS
+ S: efgh OK STARTLS completed
+ <TLS negotiation, further commands are under [TLS] layer>
+ C: ijkl CAPABILITY
+ S: * CAPABILITY IMAP4rev1 AUTH=GSSAPI AUTH=PLAIN
+ S: ijkl OK CAPABILITY completed
+
+
+6.1.2. NOOP Command
+
+ Arguments: none
+
+ Responses: no specific responses for this command (but see below)
+
+ Result: OK - noop completed
+ BAD - command unknown or arguments invalid
+
+ The NOOP command always succeeds. It does nothing.
+
+ Since any command can return a status update as untagged data, the
+ NOOP command can be used as a periodic poll for new messages or
+ message status updates during a period of inactivity (this is the
+ preferred method to do this). The NOOP command can also be used
+ to reset any inactivity autologout timer on the server.
+
+ Example: C: a002 NOOP
+ S: a002 OK NOOP completed
+ . . .
+ C: a047 NOOP
+ S: * 22 EXPUNGE
+ S: * 23 EXISTS
+ S: * 3 RECENT
+ S: * 14 FETCH (FLAGS (\Seen \Deleted))
+ S: a047 OK NOOP completed
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 25]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.1.3. LOGOUT Command
+
+ Arguments: none
+
+ Responses: REQUIRED untagged response: BYE
+
+ Result: OK - logout completed
+ BAD - command unknown or arguments invalid
+
+ The LOGOUT command informs the server that the client is done with
+ the connection. The server MUST send a BYE untagged response
+ before the (tagged) OK response, and then close the network
+ connection.
+
+ Example: C: A023 LOGOUT
+ S: * BYE IMAP4rev1 Server logging out
+ S: A023 OK LOGOUT completed
+ (Server and client then close the connection)
+
+6.2. Client Commands - Not Authenticated State
+
+ In the not authenticated state, the AUTHENTICATE or LOGIN command
+ establishes authentication and enters the authenticated state. The
+ AUTHENTICATE command provides a general mechanism for a variety of
+ authentication techniques, privacy protection, and integrity
+ checking; whereas the LOGIN command uses a traditional user name and
+ plaintext password pair and has no means of establishing privacy
+ protection or integrity checking.
+
+ The STARTTLS command is an alternate form of establishing session
+ privacy protection and integrity checking, but does not establish
+ authentication or enter the authenticated state.
+
+ Server implementations MAY allow access to certain mailboxes without
+ establishing authentication. This can be done by means of the
+ ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older
+ convention is a LOGIN command using the userid "anonymous"; in this
+ case, a password is required although the server may choose to accept
+ any password. The restrictions placed on anonymous users are
+ implementation-dependent.
+
+ Once authenticated (including as anonymous), it is not possible to
+ re-enter not authenticated state.
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 26]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
+ the following commands are valid in the not authenticated state:
+ STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations
+ section for important information about these commands.
+
+6.2.1. STARTTLS Command
+
+ Arguments: none
+
+ Responses: no specific response for this command
+
+ Result: OK - starttls completed, begin TLS negotiation
+ BAD - command unknown or arguments invalid
+
+ A [TLS] negotiation begins immediately after the CRLF at the end
+ of the tagged OK response from the server. Once a client issues a
+ STARTTLS command, it MUST NOT issue further commands until a
+ server response is seen and the [TLS] negotiation is complete.
+
+ The server remains in the non-authenticated state, even if client
+ credentials are supplied during the [TLS] negotiation. This does
+ not preclude an authentication mechanism such as EXTERNAL (defined
+ in [SASL]) from using client identity determined by the [TLS]
+ negotiation.
+
+ Once [TLS] has been started, the client MUST discard cached
+ information about server capabilities and SHOULD re-issue the
+ CAPABILITY command. This is necessary to protect against man-in-
+ the-middle attacks which alter the capabilities list prior to
+ STARTTLS. The server MAY advertise different capabilities after
+ STARTTLS.
+
+ Example: C: a001 CAPABILITY
+ S: * CAPABILITY IMAP4rev1 STARTTLS LOGINDISABLED
+ S: a001 OK CAPABILITY completed
+ C: a002 STARTTLS
+ S: a002 OK Begin TLS negotiation now
+ <TLS negotiation, further commands are under [TLS] layer>
+ C: a003 CAPABILITY
+ S: * CAPABILITY IMAP4rev1 AUTH=PLAIN
+ S: a003 OK CAPABILITY completed
+ C: a004 LOGIN joe password
+ S: a004 OK LOGIN completed
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 27]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.2.2. AUTHENTICATE Command
+
+ Arguments: authentication mechanism name
+
+ Responses: continuation data can be requested
+
+ Result: OK - authenticate completed, now in authenticated state
+ NO - authenticate failure: unsupported authentication
+ mechanism, credentials rejected
+ BAD - command unknown or arguments invalid,
+ authentication exchange cancelled
+
+ The AUTHENTICATE command indicates a [SASL] authentication
+ mechanism to the server. If the server supports the requested
+ authentication mechanism, it performs an authentication protocol
+ exchange to authenticate and identify the client. It MAY also
+ negotiate an OPTIONAL security layer for subsequent protocol
+ interactions. If the requested authentication mechanism is not
+ supported, the server SHOULD reject the AUTHENTICATE command by
+ sending a tagged NO response.
+
+ The AUTHENTICATE command does not support the optional "initial
+ response" feature of [SASL]. Section 5.1 of [SASL] specifies how
+ to handle an authentication mechanism which uses an initial
+ response.
+
+ The service name specified by this protocol's profile of [SASL] is
+ "imap".
+
+ The authentication protocol exchange consists of a series of
+ server challenges and client responses that are specific to the
+ authentication mechanism. A server challenge consists of a
+ command continuation request response with the "+" token followed
+ by a BASE64 encoded string. The client response consists of a
+ single line consisting of a BASE64 encoded string. If the client
+ wishes to cancel an authentication exchange, it issues a line
+ consisting of a single "*". If the server receives such a
+ response, it MUST reject the AUTHENTICATE command by sending a
+ tagged BAD response.
+
+ If a security layer is negotiated through the [SASL]
+ authentication exchange, it takes effect immediately following the
+ CRLF that concludes the authentication exchange for the client,
+ and the CRLF of the tagged OK response for the server.
+
+ While client and server implementations MUST implement the
+ AUTHENTICATE command itself, it is not required to implement any
+ authentication mechanisms other than the PLAIN mechanism described
+
+
+
+Crispin Standards Track [Page 28]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ in [IMAP-TLS]. Also, an authentication mechanism is not required
+ to support any security layers.
+
+ Note: a server implementation MUST implement a
+ configuration in which it does NOT permit any plaintext
+ password mechanisms, unless either the STARTTLS command
+ has been negotiated or some other mechanism that
+ protects the session from password snooping has been
+ provided. Server sites SHOULD NOT use any configuration
+ which permits a plaintext password mechanism without
+ such a protection mechanism against password snooping.
+ Client and server implementations SHOULD implement
+ additional [SASL] mechanisms that do not use plaintext
+ passwords, such the GSSAPI mechanism described in [SASL]
+ and/or the [DIGEST-MD5] mechanism.
+
+ Servers and clients can support multiple authentication
+ mechanisms. The server SHOULD list its supported authentication
+ mechanisms in the response to the CAPABILITY command so that the
+ client knows which authentication mechanisms to use.
+
+ A server MAY include a CAPABILITY response code in the tagged OK
+ response of a successful AUTHENTICATE command in order to send
+ capabilities automatically. It is unnecessary for a client to
+ send a separate CAPABILITY command if it recognizes these
+ automatic capabilities. This should only be done if a security
+ layer was not negotiated by the AUTHENTICATE command, because the
+ tagged OK response as part of an AUTHENTICATE command is not
+ protected by encryption/integrity checking. [SASL] requires the
+ client to re-issue a CAPABILITY command in this case.
+
+ If an AUTHENTICATE command fails with a NO response, the client
+ MAY try another authentication mechanism by issuing another
+ AUTHENTICATE command. It MAY also attempt to authenticate by
+ using the LOGIN command (see section 6.2.3 for more detail). In
+ other words, the client MAY request authentication types in
+ decreasing order of preference, with the LOGIN command as a last
+ resort.
+
+ The authorization identity passed from the client to the server
+ during the authentication exchange is interpreted by the server as
+ the user name whose privileges the client is requesting.
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 29]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Example: S: * OK IMAP4rev1 Server
+ C: A001 AUTHENTICATE GSSAPI
+ S: +
+ C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw
+ MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0
+ b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW
+ Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA
+ cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX
+ AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y
+ C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb
+ I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi
+ vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL
+ pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n
+ FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE
+ NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx
+ O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB
+ vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg==
+ S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC
+ AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0
+ uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg==
+ C:
+ S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe
+ ceP2CWY0SR0fAQAgAAQEBAQ=
+ C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP
+ wkhbfa2QteAQAgAG1yYwE=
+ S: A001 OK GSSAPI authentication successful
+
+ Note: The line breaks within server challenges and client
+ responses are for editorial clarity and are not in real
+ authenticators.
+
+
+6.2.3. LOGIN Command
+
+ Arguments: user name
+ password
+
+ Responses: no specific responses for this command
+
+ Result: OK - login completed, now in authenticated state
+ NO - login failure: user name or password rejected
+ BAD - command unknown or arguments invalid
+
+ The LOGIN command identifies the client to the server and carries
+ the plaintext password authenticating this user.
+
+
+
+
+
+
+Crispin Standards Track [Page 30]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ A server MAY include a CAPABILITY response code in the tagged OK
+ response to a successful LOGIN command in order to send
+ capabilities automatically. It is unnecessary for a client to
+ send a separate CAPABILITY command if it recognizes these
+ automatic capabilities.
+
+ Example: C: a001 LOGIN SMITH SESAME
+ S: a001 OK LOGIN completed
+
+ Note: Use of the LOGIN command over an insecure network
+ (such as the Internet) is a security risk, because anyone
+ monitoring network traffic can obtain plaintext passwords.
+ The LOGIN command SHOULD NOT be used except as a last
+ resort, and it is recommended that client implementations
+ have a means to disable any automatic use of the LOGIN
+ command.
+
+ Unless either the STARTTLS command has been negotiated or
+ some other mechanism that protects the session from
+ password snooping has been provided, a server
+ implementation MUST implement a configuration in which it
+ advertises the LOGINDISABLED capability and does NOT permit
+ the LOGIN command. Server sites SHOULD NOT use any
+ configuration which permits the LOGIN command without such
+ a protection mechanism against password snooping. A client
+ implementation MUST NOT send a LOGIN command if the
+ LOGINDISABLED capability is advertised.
+
+6.3. Client Commands - Authenticated State
+
+ In the authenticated state, commands that manipulate mailboxes as
+ atomic entities are permitted. Of these commands, the SELECT and
+ EXAMINE commands will select a mailbox for access and enter the
+ selected state.
+
+ In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
+ the following commands are valid in the authenticated state: SELECT,
+ EXAMINE, CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, LSUB,
+ STATUS, and APPEND.
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 31]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.3.1. SELECT Command
+
+ Arguments: mailbox name
+
+ Responses: REQUIRED untagged responses: FLAGS, EXISTS, RECENT
+ REQUIRED OK untagged responses: UNSEEN, PERMANENTFLAGS,
+ UIDNEXT, UIDVALIDITY
+
+ Result: OK - select completed, now in selected state
+ NO - select failure, now in authenticated state: no
+ such mailbox, can't access mailbox
+ BAD - command unknown or arguments invalid
+
+ The SELECT command selects a mailbox so that messages in the
+ mailbox can be accessed. Before returning an OK to the client,
+ the server MUST send the following untagged data to the client.
+ Note that earlier versions of this protocol only required the
+ FLAGS, EXISTS, and RECENT untagged data; consequently, client
+ implementations SHOULD implement default behavior for missing data
+ as discussed with the individual item.
+
+ FLAGS Defined flags in the mailbox. See the description
+ of the FLAGS response for more detail.
+
+ <n> EXISTS The number of messages in the mailbox. See the
+ description of the EXISTS response for more detail.
+
+ <n> RECENT The number of messages with the \Recent flag set.
+ See the description of the RECENT response for more
+ detail.
+
+ OK [UNSEEN <n>]
+ The message sequence number of the first unseen
+ message in the mailbox. If this is missing, the
+ client can not make any assumptions about the first
+ unseen message in the mailbox, and needs to issue a
+ SEARCH command if it wants to find it.
+
+ OK [PERMANENTFLAGS (<list of flags>)]
+ A list of message flags that the client can change
+ permanently. If this is missing, the client should
+ assume that all flags can be changed permanently.
+
+ OK [UIDNEXT <n>]
+ The next unique identifier value. Refer to section
+ 2.3.1.1 for more information. If this is missing,
+ the client can not make any assumptions about the
+ next unique identifier value.
+
+
+
+Crispin Standards Track [Page 32]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ OK [UIDVALIDITY <n>]
+ The unique identifier validity value. Refer to
+ section 2.3.1.1 for more information. If this is
+ missing, the server does not support unique
+ identifiers.
+
+ Only one mailbox can be selected at a time in a connection;
+ simultaneous access to multiple mailboxes requires multiple
+ connections. The SELECT command automatically deselects any
+ currently selected mailbox before attempting the new selection.
+ Consequently, if a mailbox is selected and a SELECT command that
+ fails is attempted, no mailbox is selected.
+
+ If the client is permitted to modify the mailbox, the server
+ SHOULD prefix the text of the tagged OK response with the
+ "[READ-WRITE]" response code.
+
+ If the client is not permitted to modify the mailbox but is
+ permitted read access, the mailbox is selected as read-only, and
+ the server MUST prefix the text of the tagged OK response to
+ SELECT with the "[READ-ONLY]" response code. Read-only access
+ through SELECT differs from the EXAMINE command in that certain
+ read-only mailboxes MAY permit the change of permanent state on a
+ per-user (as opposed to global) basis. Netnews messages marked in
+ a server-based .newsrc file are an example of such per-user
+ permanent state that can be modified with read-only mailboxes.
+
+ Example: C: A142 SELECT INBOX
+ S: * 172 EXISTS
+ S: * 1 RECENT
+ S: * OK [UNSEEN 12] Message 12 is first unseen
+ S: * OK [UIDVALIDITY 3857529045] UIDs valid
+ S: * OK [UIDNEXT 4392] Predicted next UID
+ S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
+ S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited
+ S: A142 OK [READ-WRITE] SELECT completed
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 33]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.3.2. EXAMINE Command
+
+ Arguments: mailbox name
+
+ Responses: REQUIRED untagged responses: FLAGS, EXISTS, RECENT
+ REQUIRED OK untagged responses: UNSEEN, PERMANENTFLAGS,
+ UIDNEXT, UIDVALIDITY
+
+ Result: OK - examine completed, now in selected state
+ NO - examine failure, now in authenticated state: no
+ such mailbox, can't access mailbox
+ BAD - command unknown or arguments invalid
+
+ The EXAMINE command is identical to SELECT and returns the same
+ output; however, the selected mailbox is identified as read-only.
+ No changes to the permanent state of the mailbox, including
+ per-user state, are permitted; in particular, EXAMINE MUST NOT
+ cause messages to lose the \Recent flag.
+
+ The text of the tagged OK response to the EXAMINE command MUST
+ begin with the "[READ-ONLY]" response code.
+
+ Example: C: A932 EXAMINE blurdybloop
+ S: * 17 EXISTS
+ S: * 2 RECENT
+ S: * OK [UNSEEN 8] Message 8 is first unseen
+ S: * OK [UIDVALIDITY 3857529045] UIDs valid
+ S: * OK [UIDNEXT 4392] Predicted next UID
+ S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
+ S: * OK [PERMANENTFLAGS ()] No permanent flags permitted
+ S: A932 OK [READ-ONLY] EXAMINE completed
+
+
+6.3.3. CREATE Command
+
+ Arguments: mailbox name
+
+ Responses: no specific responses for this command
+
+ Result: OK - create completed
+ NO - create failure: can't create mailbox with that name
+ BAD - command unknown or arguments invalid
+
+ The CREATE command creates a mailbox with the given name. An OK
+ response is returned only if a new mailbox with that name has been
+ created. It is an error to attempt to create INBOX or a mailbox
+ with a name that refers to an extant mailbox. Any error in
+ creation will return a tagged NO response.
+
+
+
+Crispin Standards Track [Page 34]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ If the mailbox name is suffixed with the server's hierarchy
+ separator character (as returned from the server by a LIST
+ command), this is a declaration that the client intends to create
+ mailbox names under this name in the hierarchy. Server
+ implementations that do not require this declaration MUST ignore
+ the declaration. In any case, the name created is without the
+ trailing hierarchy delimiter.
+
+ If the server's hierarchy separator character appears elsewhere in
+ the name, the server SHOULD create any superior hierarchical names
+ that are needed for the CREATE command to be successfully
+ completed. In other words, an attempt to create "foo/bar/zap" on
+ a server in which "/" is the hierarchy separator character SHOULD
+ create foo/ and foo/bar/ if they do not already exist.
+
+ If a new mailbox is created with the same name as a mailbox which
+ was deleted, its unique identifiers MUST be greater than any
+ unique identifiers used in the previous incarnation of the mailbox
+ UNLESS the new incarnation has a different unique identifier
+ validity value. See the description of the UID command for more
+ detail.
+
+ Example: C: A003 CREATE owatagusiam/
+ S: A003 OK CREATE completed
+ C: A004 CREATE owatagusiam/blurdybloop
+ S: A004 OK CREATE completed
+
+ Note: The interpretation of this example depends on whether
+ "/" was returned as the hierarchy separator from LIST. If
+ "/" is the hierarchy separator, a new level of hierarchy
+ named "owatagusiam" with a member called "blurdybloop" is
+ created. Otherwise, two mailboxes at the same hierarchy
+ level are created.
+
+
+6.3.4. DELETE Command
+
+ Arguments: mailbox name
+
+ Responses: no specific responses for this command
+
+ Result: OK - delete completed
+ NO - delete failure: can't delete mailbox with that name
+ BAD - command unknown or arguments invalid
+
+
+
+
+
+
+
+Crispin Standards Track [Page 35]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ The DELETE command permanently removes the mailbox with the given
+ name. A tagged OK response is returned only if the mailbox has
+ been deleted. It is an error to attempt to delete INBOX or a
+ mailbox name that does not exist.
+
+ The DELETE command MUST NOT remove inferior hierarchical names.
+ For example, if a mailbox "foo" has an inferior "foo.bar"
+ (assuming "." is the hierarchy delimiter character), removing
+ "foo" MUST NOT remove "foo.bar". It is an error to attempt to
+ delete a name that has inferior hierarchical names and also has
+ the \Noselect mailbox name attribute (see the description of the
+ LIST response for more details).
+
+ It is permitted to delete a name that has inferior hierarchical
+ names and does not have the \Noselect mailbox name attribute. In
+ this case, all messages in that mailbox are removed, and the name
+ will acquire the \Noselect mailbox name attribute.
+
+ The value of the highest-used unique identifier of the deleted
+ mailbox MUST be preserved so that a new mailbox created with the
+ same name will not reuse the identifiers of the former
+ incarnation, UNLESS the new incarnation has a different unique
+ identifier validity value. See the description of the UID command
+ for more detail.
+
+ Examples: C: A682 LIST "" *
+ S: * LIST () "/" blurdybloop
+ S: * LIST (\Noselect) "/" foo
+ S: * LIST () "/" foo/bar
+ S: A682 OK LIST completed
+ C: A683 DELETE blurdybloop
+ S: A683 OK DELETE completed
+ C: A684 DELETE foo
+ S: A684 NO Name "foo" has inferior hierarchical names
+ C: A685 DELETE foo/bar
+ S: A685 OK DELETE Completed
+ C: A686 LIST "" *
+ S: * LIST (\Noselect) "/" foo
+ S: A686 OK LIST completed
+ C: A687 DELETE foo
+ S: A687 OK DELETE Completed
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 36]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ C: A82 LIST "" *
+ S: * LIST () "." blurdybloop
+ S: * LIST () "." foo
+ S: * LIST () "." foo.bar
+ S: A82 OK LIST completed
+ C: A83 DELETE blurdybloop
+ S: A83 OK DELETE completed
+ C: A84 DELETE foo
+ S: A84 OK DELETE Completed
+ C: A85 LIST "" *
+ S: * LIST () "." foo.bar
+ S: A85 OK LIST completed
+ C: A86 LIST "" %
+ S: * LIST (\Noselect) "." foo
+ S: A86 OK LIST completed
+
+
+6.3.5. RENAME Command
+
+ Arguments: existing mailbox name
+ new mailbox name
+
+ Responses: no specific responses for this command
+
+ Result: OK - rename completed
+ NO - rename failure: can't rename mailbox with that name,
+ can't rename to mailbox with that name
+ BAD - command unknown or arguments invalid
+
+ The RENAME command changes the name of a mailbox. A tagged OK
+ response is returned only if the mailbox has been renamed. It is
+ an error to attempt to rename from a mailbox name that does not
+ exist or to a mailbox name that already exists. Any error in
+ renaming will return a tagged NO response.
+
+ If the name has inferior hierarchical names, then the inferior
+ hierarchical names MUST also be renamed. For example, a rename of
+ "foo" to "zap" will rename "foo/bar" (assuming "/" is the
+ hierarchy delimiter character) to "zap/bar".
+
+ If the server's hierarchy separator character appears in the name,
+ the server SHOULD create any superior hierarchical names that are
+ needed for the RENAME command to complete successfully. In other
+ words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a
+ server in which "/" is the hierarchy separator character SHOULD
+ create baz/ and baz/rag/ if they do not already exist.
+
+
+
+
+
+Crispin Standards Track [Page 37]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ The value of the highest-used unique identifier of the old mailbox
+ name MUST be preserved so that a new mailbox created with the same
+ name will not reuse the identifiers of the former incarnation,
+ UNLESS the new incarnation has a different unique identifier
+ validity value. See the description of the UID command for more
+ detail.
+
+ Renaming INBOX is permitted, and has special behavior. It moves
+ all messages in INBOX to a new mailbox with the given name,
+ leaving INBOX empty. If the server implementation supports
+ inferior hierarchical names of INBOX, these are unaffected by a
+ rename of INBOX.
+
+ Examples: C: A682 LIST "" *
+ S: * LIST () "/" blurdybloop
+ S: * LIST (\Noselect) "/" foo
+ S: * LIST () "/" foo/bar
+ S: A682 OK LIST completed
+ C: A683 RENAME blurdybloop sarasoop
+ S: A683 OK RENAME completed
+ C: A684 RENAME foo zowie
+ S: A684 OK RENAME Completed
+ C: A685 LIST "" *
+ S: * LIST () "/" sarasoop
+ S: * LIST (\Noselect) "/" zowie
+ S: * LIST () "/" zowie/bar
+ S: A685 OK LIST completed
+
+ C: Z432 LIST "" *
+ S: * LIST () "." INBOX
+ S: * LIST () "." INBOX.bar
+ S: Z432 OK LIST completed
+ C: Z433 RENAME INBOX old-mail
+ S: Z433 OK RENAME completed
+ C: Z434 LIST "" *
+ S: * LIST () "." INBOX
+ S: * LIST () "." INBOX.bar
+ S: * LIST () "." old-mail
+ S: Z434 OK LIST completed
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 38]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.3.6. SUBSCRIBE Command
+
+ Arguments: mailbox
+
+ Responses: no specific responses for this command
+
+ Result: OK - subscribe completed
+ NO - subscribe failure: can't subscribe to that name
+ BAD - command unknown or arguments invalid
+
+ The SUBSCRIBE command adds the specified mailbox name to the
+ server's set of "active" or "subscribed" mailboxes as returned by
+ the LSUB command. This command returns a tagged OK response only
+ if the subscription is successful.
+
+ A server MAY validate the mailbox argument to SUBSCRIBE to verify
+ that it exists. However, it MUST NOT unilaterally remove an
+ existing mailbox name from the subscription list even if a mailbox
+ by that name no longer exists.
+
+ Note: This requirement is because a server site can
+ choose to routinely remove a mailbox with a well-known
+ name (e.g., "system-alerts") after its contents expire,
+ with the intention of recreating it when new contents
+ are appropriate.
+
+
+ Example: C: A002 SUBSCRIBE #news.comp.mail.mime
+ S: A002 OK SUBSCRIBE completed
+
+
+6.3.7. UNSUBSCRIBE Command
+
+ Arguments: mailbox name
+
+ Responses: no specific responses for this command
+
+ Result: OK - unsubscribe completed
+ NO - unsubscribe failure: can't unsubscribe that name
+ BAD - command unknown or arguments invalid
+
+ The UNSUBSCRIBE command removes the specified mailbox name from
+ the server's set of "active" or "subscribed" mailboxes as returned
+ by the LSUB command. This command returns a tagged OK response
+ only if the unsubscription is successful.
+
+ Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime
+ S: A002 OK UNSUBSCRIBE completed
+
+
+
+Crispin Standards Track [Page 39]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.3.8. LIST Command
+
+ Arguments: reference name
+ mailbox name with possible wildcards
+
+ Responses: untagged responses: LIST
+
+ Result: OK - list completed
+ NO - list failure: can't list that reference or name
+ BAD - command unknown or arguments invalid
+
+ The LIST command returns a subset of names from the complete set
+ of all names available to the client. Zero or more untagged LIST
+ replies are returned, containing the name attributes, hierarchy
+ delimiter, and name; see the description of the LIST reply for
+ more detail.
+
+ The LIST command SHOULD return its data quickly, without undue
+ delay. For example, it SHOULD NOT go to excess trouble to
+ calculate the \Marked or \Unmarked status or perform other
+ processing; if each name requires 1 second of processing, then a
+ list of 1200 names would take 20 minutes!
+
+ An empty ("" string) reference name argument indicates that the
+ mailbox name is interpreted as by SELECT. The returned mailbox
+ names MUST match the supplied mailbox name pattern. A non-empty
+ reference name argument is the name of a mailbox or a level of
+ mailbox hierarchy, and indicates the context in which the mailbox
+ name is interpreted.
+
+ An empty ("" string) mailbox name argument is a special request to
+ return the hierarchy delimiter and the root name of the name given
+ in the reference. The value returned as the root MAY be the empty
+ string if the reference is non-rooted or is an empty string. In
+ all cases, a hierarchy delimiter (or NIL if there is no hierarchy)
+ is returned. This permits a client to get the hierarchy delimiter
+ (or find out that the mailbox names are flat) even when no
+ mailboxes by that name currently exist.
+
+ The reference and mailbox name arguments are interpreted into a
+ canonical form that represents an unambiguous left-to-right
+ hierarchy. The returned mailbox names will be in the interpreted
+ form.
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 40]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Note: The interpretation of the reference argument is
+ implementation-defined. It depends upon whether the
+ server implementation has a concept of the "current
+ working directory" and leading "break out characters",
+ which override the current working directory.
+
+ For example, on a server which exports a UNIX or NT
+ filesystem, the reference argument contains the current
+ working directory, and the mailbox name argument would
+ contain the name as interpreted in the current working
+ directory.
+
+ If a server implementation has no concept of break out
+ characters, the canonical form is normally the reference
+ name appended with the mailbox name. Note that if the
+ server implements the namespace convention (section
+ 5.1.2), "#" is a break out character and must be treated
+ as such.
+
+ If the reference argument is not a level of mailbox
+ hierarchy (that is, it is a \NoInferiors name), and/or
+ the reference argument does not end with the hierarchy
+ delimiter, it is implementation-dependent how this is
+ interpreted. For example, a reference of "foo/bar" and
+ mailbox name of "rag/baz" could be interpreted as
+ "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/baz".
+ A client SHOULD NOT use such a reference argument except
+ at the explicit request of the user. A hierarchical
+ browser MUST NOT make any assumptions about server
+ interpretation of the reference unless the reference is
+ a level of mailbox hierarchy AND ends with the hierarchy
+ delimiter.
+
+ Any part of the reference argument that is included in the
+ interpreted form SHOULD prefix the interpreted form. It SHOULD
+ also be in the same form as the reference name argument. This
+ rule permits the client to determine if the returned mailbox name
+ is in the context of the reference argument, or if something about
+ the mailbox argument overrode the reference argument. Without
+ this rule, the client would have to have knowledge of the server's
+ naming semantics including what characters are "breakouts" that
+ override a naming context.
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 41]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ For example, here are some examples of how references
+ and mailbox names might be interpreted on a UNIX-based
+ server:
+
+ Reference Mailbox Name Interpretation
+ ------------ ------------ --------------
+ ~smith/Mail/ foo.* ~smith/Mail/foo.*
+ archive/ % archive/%
+ #news. comp.mail.* #news.comp.mail.*
+ ~smith/Mail/ /usr/doc/foo /usr/doc/foo
+ archive/ ~fred/Mail/* ~fred/Mail/*
+
+ The first three examples demonstrate interpretations in
+ the context of the reference argument. Note that
+ "~smith/Mail" SHOULD NOT be transformed into something
+ like "/u2/users/smith/Mail", or it would be impossible
+ for the client to determine that the interpretation was
+ in the context of the reference.
+
+ The character "*" is a wildcard, and matches zero or more
+ characters at this position. The character "%" is similar to "*",
+ but it does not match a hierarchy delimiter. If the "%" wildcard
+ is the last character of a mailbox name argument, matching levels
+ of hierarchy are also returned. If these levels of hierarchy are
+ not also selectable mailboxes, they are returned with the
+ \Noselect mailbox name attribute (see the description of the LIST
+ response for more details).
+
+ Server implementations are permitted to "hide" otherwise
+ accessible mailboxes from the wildcard characters, by preventing
+ certain characters or names from matching a wildcard in certain
+ situations. For example, a UNIX-based server might restrict the
+ interpretation of "*" so that an initial "/" character does not
+ match.
+
+ The special name INBOX is included in the output from LIST, if
+ INBOX is supported by this server for this user and if the
+ uppercase string "INBOX" matches the interpreted reference and
+ mailbox name arguments with wildcards as described above. The
+ criteria for omitting INBOX is whether SELECT INBOX will return
+ failure; it is not relevant whether the user's real INBOX resides
+ on this or some other server.
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 42]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Example: C: A101 LIST "" ""
+ S: * LIST (\Noselect) "/" ""
+ S: A101 OK LIST Completed
+ C: A102 LIST #news.comp.mail.misc ""
+ S: * LIST (\Noselect) "." #news.
+ S: A102 OK LIST Completed
+ C: A103 LIST /usr/staff/jones ""
+ S: * LIST (\Noselect) "/" /
+ S: A103 OK LIST Completed
+ C: A202 LIST ~/Mail/ %
+ S: * LIST (\Noselect) "/" ~/Mail/foo
+ S: * LIST () "/" ~/Mail/meetings
+ S: A202 OK LIST completed
+
+
+6.3.9. LSUB Command
+
+ Arguments: reference name
+ mailbox name with possible wildcards
+
+ Responses: untagged responses: LSUB
+
+ Result: OK - lsub completed
+ NO - lsub failure: can't list that reference or name
+ BAD - command unknown or arguments invalid
+
+ The LSUB command returns a subset of names from the set of names
+ that the user has declared as being "active" or "subscribed".
+ Zero or more untagged LSUB replies are returned. The arguments to
+ LSUB are in the same form as those for LIST.
+
+ The returned untagged LSUB response MAY contain different mailbox
+ flags from a LIST untagged response. If this should happen, the
+ flags in the untagged LIST are considered more authoritative.
+
+ A special situation occurs when using LSUB with the % wildcard.
+ Consider what happens if "foo/bar" (with a hierarchy delimiter of
+ "/") is subscribed but "foo" is not. A "%" wildcard to LSUB must
+ return foo, not foo/bar, in the LSUB response, and it MUST be
+ flagged with the \Noselect attribute.
+
+ The server MUST NOT unilaterally remove an existing mailbox name
+ from the subscription list even if a mailbox by that name no
+ longer exists.
+
+
+
+
+
+
+
+Crispin Standards Track [Page 43]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Example: C: A002 LSUB "#news." "comp.mail.*"
+ S: * LSUB () "." #news.comp.mail.mime
+ S: * LSUB () "." #news.comp.mail.misc
+ S: A002 OK LSUB completed
+ C: A003 LSUB "#news." "comp.%"
+ S: * LSUB (\NoSelect) "." #news.comp.mail
+ S: A003 OK LSUB completed
+
+
+6.3.10. STATUS Command
+
+ Arguments: mailbox name
+ status data item names
+
+ Responses: untagged responses: STATUS
+
+ Result: OK - status completed
+ NO - status failure: no status for that name
+ BAD - command unknown or arguments invalid
+
+ The STATUS command requests the status of the indicated mailbox.
+ It does not change the currently selected mailbox, nor does it
+ affect the state of any messages in the queried mailbox (in
+ particular, STATUS MUST NOT cause messages to lose the \Recent
+ flag).
+
+ The STATUS command provides an alternative to opening a second
+ IMAP4rev1 connection and doing an EXAMINE command on a mailbox to
+ query that mailbox's status without deselecting the current
+ mailbox in the first IMAP4rev1 connection.
+
+ Unlike the LIST command, the STATUS command is not guaranteed to
+ be fast in its response. Under certain circumstances, it can be
+ quite slow. In some implementations, the server is obliged to
+ open the mailbox read-only internally to obtain certain status
+ information. Also unlike the LIST command, the STATUS command
+ does not accept wildcards.
+
+ Note: The STATUS command is intended to access the
+ status of mailboxes other than the currently selected
+ mailbox. Because the STATUS command can cause the
+ mailbox to be opened internally, and because this
+ information is available by other means on the selected
+ mailbox, the STATUS command SHOULD NOT be used on the
+ currently selected mailbox.
+
+
+
+
+
+
+Crispin Standards Track [Page 44]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ The STATUS command MUST NOT be used as a "check for new
+ messages in the selected mailbox" operation (refer to
+ sections 7, 7.3.1, and 7.3.2 for more information about
+ the proper method for new message checking).
+
+ Because the STATUS command is not guaranteed to be fast
+ in its results, clients SHOULD NOT expect to be able to
+ issue many consecutive STATUS commands and obtain
+ reasonable performance.
+
+ The currently defined status data items that can be requested are:
+
+ MESSAGES
+ The number of messages in the mailbox.
+
+ RECENT
+ The number of messages with the \Recent flag set.
+
+ UIDNEXT
+ The next unique identifier value of the mailbox. Refer to
+ section 2.3.1.1 for more information.
+
+ UIDVALIDITY
+ The unique identifier validity value of the mailbox. Refer to
+ section 2.3.1.1 for more information.
+
+ UNSEEN
+ The number of messages which do not have the \Seen flag set.
+
+
+ Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES)
+ S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292)
+ S: A042 OK STATUS completed
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 45]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.3.11. APPEND Command
+
+ Arguments: mailbox name
+ OPTIONAL flag parenthesized list
+ OPTIONAL date/time string
+ message literal
+
+ Responses: no specific responses for this command
+
+ Result: OK - append completed
+ NO - append error: can't append to that mailbox, error
+ in flags or date/time or message text
+ BAD - command unknown or arguments invalid
+
+ The APPEND command appends the literal argument as a new message
+ to the end of the specified destination mailbox. This argument
+ SHOULD be in the format of an [RFC-2822] message. 8-bit
+ characters are permitted in the message. A server implementation
+ that is unable to preserve 8-bit data properly MUST be able to
+ reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB]
+ content transfer encoding.
+
+ Note: There MAY be exceptions, e.g., draft messages, in
+ which required [RFC-2822] header lines are omitted in
+ the message literal argument to APPEND. The full
+ implications of doing so MUST be understood and
+ carefully weighed.
+
+ If a flag parenthesized list is specified, the flags SHOULD be set
+ in the resulting message; otherwise, the flag list of the
+ resulting message is set to empty by default. In either case, the
+ Recent flag is also set.
+
+ If a date-time is specified, the internal date SHOULD be set in
+ the resulting message; otherwise, the internal date of the
+ resulting message is set to the current date and time by default.
+
+ If the append is unsuccessful for any reason, the mailbox MUST be
+ restored to its state before the APPEND attempt; no partial
+ appending is permitted.
+
+ If the destination mailbox does not exist, a server MUST return an
+ error, and MUST NOT automatically create the mailbox. Unless it
+ is certain that the destination mailbox can not be created, the
+ server MUST send the response code "[TRYCREATE]" as the prefix of
+ the text of the tagged NO response. This gives a hint to the
+ client that it can attempt a CREATE command and retry the APPEND
+ if the CREATE is successful.
+
+
+
+Crispin Standards Track [Page 46]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ If the mailbox is currently selected, the normal new message
+ actions SHOULD occur. Specifically, the server SHOULD notify the
+ client immediately via an untagged EXISTS response. If the server
+ does not do so, the client MAY issue a NOOP command (or failing
+ that, a CHECK command) after one or more APPEND commands.
+
+ Example: C: A003 APPEND saved-messages (\Seen) {310}
+ S: + Ready for literal data
+ C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)
+ C: From: Fred Foobar <foobar@Blurdybloop.COM>
+ C: Subject: afternoon meeting
+ C: To: mooch@owatagu.siam.edu
+ C: Message-Id: <B27397-0100000@Blurdybloop.COM>
+ C: MIME-Version: 1.0
+ C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
+ C:
+ C: Hello Joe, do you think we can meet at 3:30 tomorrow?
+ C:
+ S: A003 OK APPEND completed
+
+ Note: The APPEND command is not used for message delivery,
+ because it does not provide a mechanism to transfer [SMTP]
+ envelope information.
+
+6.4. Client Commands - Selected State
+
+ In the selected state, commands that manipulate messages in a mailbox
+ are permitted.
+
+ In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
+ and the authenticated state commands (SELECT, EXAMINE, CREATE,
+ DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, LSUB, STATUS, and
+ APPEND), the following commands are valid in the selected state:
+ CHECK, CLOSE, EXPUNGE, SEARCH, FETCH, STORE, COPY, and UID.
+
+6.4.1. CHECK Command
+
+ Arguments: none
+
+ Responses: no specific responses for this command
+
+ Result: OK - check completed
+ BAD - command unknown or arguments invalid
+
+ The CHECK command requests a checkpoint of the currently selected
+ mailbox. A checkpoint refers to any implementation-dependent
+ housekeeping associated with the mailbox (e.g., resolving the
+ server's in-memory state of the mailbox with the state on its
+
+
+
+Crispin Standards Track [Page 47]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ disk) that is not normally executed as part of each command. A
+ checkpoint MAY take a non-instantaneous amount of real time to
+ complete. If a server implementation has no such housekeeping
+ considerations, CHECK is equivalent to NOOP.
+
+ There is no guarantee that an EXISTS untagged response will happen
+ as a result of CHECK. NOOP, not CHECK, SHOULD be used for new
+ message polling.
+
+ Example: C: FXXZ CHECK
+ S: FXXZ OK CHECK Completed
+
+
+6.4.2. CLOSE Command
+
+ Arguments: none
+
+ Responses: no specific responses for this command
+
+ Result: OK - close completed, now in authenticated state
+ BAD - command unknown or arguments invalid
+
+ The CLOSE command permanently removes all messages that have the
+ \Deleted flag set from the currently selected mailbox, and returns
+ to the authenticated state from the selected state. No untagged
+ EXPUNGE responses are sent.
+
+ No messages are removed, and no error is given, if the mailbox is
+ selected by an EXAMINE command or is otherwise selected read-only.
+
+ Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT
+ command MAY be issued without previously issuing a CLOSE command.
+ The SELECT, EXAMINE, and LOGOUT commands implicitly close the
+ currently selected mailbox without doing an expunge. However,
+ when many messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT
+ sequence is considerably faster than an EXPUNGE-LOGOUT or
+ EXPUNGE-SELECT because no untagged EXPUNGE responses (which the
+ client would probably ignore) are sent.
+
+ Example: C: A341 CLOSE
+ S: A341 OK CLOSE completed
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 48]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.4.3. EXPUNGE Command
+
+ Arguments: none
+
+ Responses: untagged responses: EXPUNGE
+
+ Result: OK - expunge completed
+ NO - expunge failure: can't expunge (e.g., permission
+ denied)
+ BAD - command unknown or arguments invalid
+
+ The EXPUNGE command permanently removes all messages that have the
+ \Deleted flag set from the currently selected mailbox. Before
+ returning an OK to the client, an untagged EXPUNGE response is
+ sent for each message that is removed.
+
+ Example: C: A202 EXPUNGE
+ S: * 3 EXPUNGE
+ S: * 3 EXPUNGE
+ S: * 5 EXPUNGE
+ S: * 8 EXPUNGE
+ S: A202 OK EXPUNGE completed
+
+ Note: In this example, messages 3, 4, 7, and 11 had the
+ \Deleted flag set. See the description of the EXPUNGE
+ response for further explanation.
+
+
+6.4.4. SEARCH Command
+
+ Arguments: OPTIONAL [CHARSET] specification
+ searching criteria (one or more)
+
+ Responses: REQUIRED untagged response: SEARCH
+
+ Result: OK - search completed
+ NO - search error: can't search that [CHARSET] or
+ criteria
+ BAD - command unknown or arguments invalid
+
+ The SEARCH command searches the mailbox for messages that match
+ the given searching criteria. Searching criteria consist of one
+ or more search keys. The untagged SEARCH response from the server
+ contains a listing of message sequence numbers corresponding to
+ those messages that match the searching criteria.
+
+
+
+
+
+
+Crispin Standards Track [Page 49]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ When multiple keys are specified, the result is the intersection
+ (AND function) of all the messages that match those keys. For
+ example, the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers
+ to all deleted messages from Smith that were placed in the mailbox
+ since February 1, 1994. A search key can also be a parenthesized
+ list of one or more search keys (e.g., for use with the OR and NOT
+ keys).
+
+ Server implementations MAY exclude [MIME-IMB] body parts with
+ terminal content media types other than TEXT and MESSAGE from
+ consideration in SEARCH matching.
+
+ The OPTIONAL [CHARSET] specification consists of the word
+ "CHARSET" followed by a registered [CHARSET]. It indicates the
+ [CHARSET] of the strings that appear in the search criteria.
+ [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in
+ [RFC-2822]/[MIME-IMB] headers, MUST be decoded before comparing
+ text in a [CHARSET] other than US-ASCII. US-ASCII MUST be
+ supported; other [CHARSET]s MAY be supported.
+
+ If the server does not support the specified [CHARSET], it MUST
+ return a tagged NO response (not a BAD). This response SHOULD
+ contain the BADCHARSET response code, which MAY list the
+ [CHARSET]s supported by the server.
+
+ In all search keys that use strings, a message matches the key if
+ the string is a substring of the field. The matching is
+ case-insensitive.
+
+ The defined search keys are as follows. Refer to the Formal
+ Syntax section for the precise syntactic definitions of the
+ arguments.
+
+ <sequence set>
+ Messages with message sequence numbers corresponding to the
+ specified message sequence number set.
+
+ ALL
+ All messages in the mailbox; the default initial key for
+ ANDing.
+
+ ANSWERED
+ Messages with the \Answered flag set.
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 50]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ BCC <string>
+ Messages that contain the specified string in the envelope
+ structure's BCC field.
+
+ BEFORE <date>
+ Messages whose internal date (disregarding time and timezone)
+ is earlier than the specified date.
+
+ BODY <string>
+ Messages that contain the specified string in the body of the
+ message.
+
+ CC <string>
+ Messages that contain the specified string in the envelope
+ structure's CC field.
+
+ DELETED
+ Messages with the \Deleted flag set.
+
+ DRAFT
+ Messages with the \Draft flag set.
+
+ FLAGGED
+ Messages with the \Flagged flag set.
+
+ FROM <string>
+ Messages that contain the specified string in the envelope
+ structure's FROM field.
+
+ HEADER <field-name> <string>
+ Messages that have a header with the specified field-name (as
+ defined in [RFC-2822]) and that contains the specified string
+ in the text of the header (what comes after the colon). If the
+ string to search is zero-length, this matches all messages that
+ have a header line with the specified field-name regardless of
+ the contents.
+
+ KEYWORD <flag>
+ Messages with the specified keyword flag set.
+
+ LARGER <n>
+ Messages with an [RFC-2822] size larger than the specified
+ number of octets.
+
+ NEW
+ Messages that have the \Recent flag set but not the \Seen flag.
+ This is functionally equivalent to "(RECENT UNSEEN)".
+
+
+
+
+Crispin Standards Track [Page 51]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ NOT <search-key>
+ Messages that do not match the specified search key.
+
+ OLD
+ Messages that do not have the \Recent flag set. This is
+ functionally equivalent to "NOT RECENT" (as opposed to "NOT
+ NEW").
+
+ ON <date>
+ Messages whose internal date (disregarding time and timezone)
+ is within the specified date.
+
+ OR <search-key1> <search-key2>
+ Messages that match either search key.
+
+ RECENT
+ Messages that have the \Recent flag set.
+
+ SEEN
+ Messages that have the \Seen flag set.
+
+ SENTBEFORE <date>
+ Messages whose [RFC-2822] Date: header (disregarding time and
+ timezone) is earlier than the specified date.
+
+ SENTON <date>
+ Messages whose [RFC-2822] Date: header (disregarding time and
+ timezone) is within the specified date.
+
+ SENTSINCE <date>
+ Messages whose [RFC-2822] Date: header (disregarding time and
+ timezone) is within or later than the specified date.
+
+ SINCE <date>
+ Messages whose internal date (disregarding time and timezone)
+ is within or later than the specified date.
+
+ SMALLER <n>
+ Messages with an [RFC-2822] size smaller than the specified
+ number of octets.
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 52]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ SUBJECT <string>
+ Messages that contain the specified string in the envelope
+ structure's SUBJECT field.
+
+ TEXT <string>
+ Messages that contain the specified string in the header or
+ body of the message.
+
+ TO <string>
+ Messages that contain the specified string in the envelope
+ structure's TO field.
+
+ UID <sequence set>
+ Messages with unique identifiers corresponding to the specified
+ unique identifier set. Sequence set ranges are permitted.
+
+ UNANSWERED
+ Messages that do not have the \Answered flag set.
+
+ UNDELETED
+ Messages that do not have the \Deleted flag set.
+
+ UNDRAFT
+ Messages that do not have the \Draft flag set.
+
+ UNFLAGGED
+ Messages that do not have the \Flagged flag set.
+
+ UNKEYWORD <flag>
+ Messages that do not have the specified keyword flag set.
+
+ UNSEEN
+ Messages that do not have the \Seen flag set.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 53]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Example: C: A282 SEARCH FLAGGED SINCE 1-Feb-1994 NOT FROM "Smith"
+ S: * SEARCH 2 84 882
+ S: A282 OK SEARCH completed
+ C: A283 SEARCH TEXT "string not in mailbox"
+ S: * SEARCH
+ S: A283 OK SEARCH completed
+ C: A284 SEARCH CHARSET UTF-8 TEXT {6}
+ C: XXXXXX
+ S: * SEARCH 43
+ S: A284 OK SEARCH completed
+
+ Note: Since this document is restricted to 7-bit ASCII
+ text, it is not possible to show actual UTF-8 data. The
+ "XXXXXX" is a placeholder for what would be 6 octets of
+ 8-bit data in an actual transaction.
+
+
+6.4.5. FETCH Command
+
+ Arguments: sequence set
+ message data item names or macro
+
+ Responses: untagged responses: FETCH
+
+ Result: OK - fetch completed
+ NO - fetch error: can't fetch that data
+ BAD - command unknown or arguments invalid
+
+ The FETCH command retrieves data associated with a message in the
+ mailbox. The data items to be fetched can be either a single atom
+ or a parenthesized list.
+
+ Most data items, identified in the formal syntax under the
+ msg-att-static rule, are static and MUST NOT change for any
+ particular message. Other data items, identified in the formal
+ syntax under the msg-att-dynamic rule, MAY change, either as a
+ result of a STORE command or due to external events.
+
+ For example, if a client receives an ENVELOPE for a
+ message when it already knows the envelope, it can
+ safely ignore the newly transmitted envelope.
+
+ There are three macros which specify commonly-used sets of data
+ items, and can be used instead of data items. A macro must be
+ used by itself, and not in conjunction with other macros or data
+ items.
+
+
+
+
+
+Crispin Standards Track [Page 54]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ ALL
+ Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE)
+
+ FAST
+ Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE)
+
+ FULL
+ Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE
+ BODY)
+
+ The currently defined data items that can be fetched are:
+
+ BODY
+ Non-extensible form of BODYSTRUCTURE.
+
+ BODY[<section>]<<partial>>
+ The text of a particular body section. The section
+ specification is a set of zero or more part specifiers
+ delimited by periods. A part specifier is either a part number
+ or one of the following: HEADER, HEADER.FIELDS,
+ HEADER.FIELDS.NOT, MIME, and TEXT. An empty section
+ specification refers to the entire message, including the
+ header.
+
+ Every message has at least one part number. Non-[MIME-IMB]
+ messages, and non-multipart [MIME-IMB] messages with no
+ encapsulated message, only have a part 1.
+
+ Multipart messages are assigned consecutive part numbers, as
+ they occur in the message. If a particular part is of type
+ message or multipart, its parts MUST be indicated by a period
+ followed by the part number within that nested multipart part.
+
+ A part of type MESSAGE/RFC822 also has nested part numbers,
+ referring to parts of the MESSAGE part's body.
+
+ The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part
+ specifiers can be the sole part specifier or can be prefixed by
+ one or more numeric part specifiers, provided that the numeric
+ part specifier refers to a part of type MESSAGE/RFC822. The
+ MIME part specifier MUST be prefixed by one or more numeric
+ part specifiers.
+
+ The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part
+ specifiers refer to the [RFC-2822] header of the message or of
+ an encapsulated [MIME-IMT] MESSAGE/RFC822 message.
+ HEADER.FIELDS and HEADER.FIELDS.NOT are followed by a list of
+ field-name (as defined in [RFC-2822]) names, and return a
+
+
+
+Crispin Standards Track [Page 55]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ subset of the header. The subset returned by HEADER.FIELDS
+ contains only those header fields with a field-name that
+ matches one of the names in the list; similarly, the subset
+ returned by HEADER.FIELDS.NOT contains only the header fields
+ with a non-matching field-name. The field-matching is
+ case-insensitive but otherwise exact. Subsetting does not
+ exclude the [RFC-2822] delimiting blank line between the header
+ and the body; the blank line is included in all header fetches,
+ except in the case of a message which has no body and no blank
+ line.
+
+ The MIME part specifier refers to the [MIME-IMB] header for
+ this part.
+
+ The TEXT part specifier refers to the text body of the message,
+ omitting the [RFC-2822] header.
+
+ Here is an example of a complex message with some of its
+ part specifiers:
+
+ HEADER ([RFC-2822] header of the message)
+ TEXT ([RFC-2822] text body of the message) MULTIPART/MIXED
+ 1 TEXT/PLAIN
+ 2 APPLICATION/OCTET-STREAM
+ 3 MESSAGE/RFC822
+ 3.HEADER ([RFC-2822] header of the message)
+ 3.TEXT ([RFC-2822] text body of the message) MULTIPART/MIXED
+ 3.1 TEXT/PLAIN
+ 3.2 APPLICATION/OCTET-STREAM
+ 4 MULTIPART/MIXED
+ 4.1 IMAGE/GIF
+ 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF)
+ 4.2 MESSAGE/RFC822
+ 4.2.HEADER ([RFC-2822] header of the message)
+ 4.2.TEXT ([RFC-2822] text body of the message) MULTIPART/MIXED
+ 4.2.1 TEXT/PLAIN
+ 4.2.2 MULTIPART/ALTERNATIVE
+ 4.2.2.1 TEXT/PLAIN
+ 4.2.2.2 TEXT/RICHTEXT
+
+
+ It is possible to fetch a substring of the designated text.
+ This is done by appending an open angle bracket ("<"), the
+ octet position of the first desired octet, a period, the
+ maximum number of octets desired, and a close angle bracket
+ (">") to the part specifier. If the starting octet is beyond
+ the end of the text, an empty string is returned.
+
+
+
+
+Crispin Standards Track [Page 56]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ Any partial fetch that attempts to read beyond the end of the
+ text is truncated as appropriate. A partial fetch that starts
+ at octet 0 is returned as a partial fetch, even if this
+ truncation happened.
+
+ Note: This means that BODY[]<0.2048> of a 1500-octet message
+ will return BODY[]<0> with a literal of size 1500, not
+ BODY[].
+
+ Note: A substring fetch of a HEADER.FIELDS or
+ HEADER.FIELDS.NOT part specifier is calculated after
+ subsetting the header.
+
+ The \Seen flag is implicitly set; if this causes the flags to
+ change, they SHOULD be included as part of the FETCH responses.
+
+ BODY.PEEK[<section>]<<partial>>
+ An alternate form of BODY[<section>] that does not implicitly
+ set the \Seen flag.
+
+ BODYSTRUCTURE
+ The [MIME-IMB] body structure of the message. This is computed
+ by the server by parsing the [MIME-IMB] header fields in the
+ [RFC-2822] header and [MIME-IMB] headers.
+
+ ENVELOPE
+ The envelope structure of the message. This is computed by the
+ server by parsing the [RFC-2822] header into the component
+ parts, defaulting various fields as necessary.
+
+ FLAGS
+ The flags that are set for this message.
+
+ INTERNALDATE
+ The internal date of the message.
+
+ RFC822
+ Functionally equivalent to BODY[], differing in the syntax of
+ the resulting untagged FETCH data (RFC822 is returned).
+
+ RFC822.HEADER
+ Functionally equivalent to BODY.PEEK[HEADER], differing in the
+ syntax of the resulting untagged FETCH data (RFC822.HEADER is
+ returned).
+
+ RFC822.SIZE
+ The [RFC-2822] size of the message.
+
+
+
+
+Crispin Standards Track [Page 57]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ RFC822.TEXT
+ Functionally equivalent to BODY[TEXT], differing in the syntax
+ of the resulting untagged FETCH data (RFC822.TEXT is returned).
+
+ UID
+ The unique identifier for the message.
+
+
+ Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)])
+ S: * 2 FETCH ....
+ S: * 3 FETCH ....
+ S: * 4 FETCH ....
+ S: A654 OK FETCH completed
+
+
+6.4.6. STORE Command
+
+ Arguments: sequence set
+ message data item name
+ value for message data item
+
+ Responses: untagged responses: FETCH
+
+ Result: OK - store completed
+ NO - store error: can't store that data
+ BAD - command unknown or arguments invalid
+
+ The STORE command alters data associated with a message in the
+ mailbox. Normally, STORE will return the updated value of the
+ data with an untagged FETCH response. A suffix of ".SILENT" in
+ the data item name prevents the untagged FETCH, and the server
+ SHOULD assume that the client has determined the updated value
+ itself or does not care about the updated value.
+
+ Note: Regardless of whether or not the ".SILENT" suffix
+ was used, the server SHOULD send an untagged FETCH
+ response if a change to a message's flags from an
+ external source is observed. The intent is that the
+ status of the flags is determinate without a race
+ condition.
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 58]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ The currently defined data items that can be stored are:
+
+ FLAGS <flag list>
+ Replace the flags for the message (other than \Recent) with the
+ argument. The new value of the flags is returned as if a FETCH
+ of those flags was done.
+
+ FLAGS.SILENT <flag list>
+ Equivalent to FLAGS, but without returning a new value.
+
+ +FLAGS <flag list>
+ Add the argument to the flags for the message. The new value
+ of the flags is returned as if a FETCH of those flags was done.
+
+ +FLAGS.SILENT <flag list>
+ Equivalent to +FLAGS, but without returning a new value.
+
+ -FLAGS <flag list>
+ Remove the argument from the flags for the message. The new
+ value of the flags is returned as if a FETCH of those flags was
+ done.
+
+ -FLAGS.SILENT <flag list>
+ Equivalent to -FLAGS, but without returning a new value.
+
+
+ Example: C: A003 STORE 2:4 +FLAGS (\Deleted)
+ S: * 2 FETCH (FLAGS (\Deleted \Seen))
+ S: * 3 FETCH (FLAGS (\Deleted))
+ S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen))
+ S: A003 OK STORE completed
+
+
+6.4.7. COPY Command
+
+ Arguments: sequence set
+ mailbox name
+
+ Responses: no specific responses for this command
+
+ Result: OK - copy completed
+ NO - copy error: can't copy those messages or to that
+ name
+ BAD - command unknown or arguments invalid
+
+
+
+
+
+
+
+Crispin Standards Track [Page 59]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ The COPY command copies the specified message(s) to the end of the
+ specified destination mailbox. The flags and internal date of the
+ message(s) SHOULD be preserved, and the Recent flag SHOULD be set,
+ in the copy.
+
+ If the destination mailbox does not exist, a server SHOULD return
+ an error. It SHOULD NOT automatically create the mailbox. Unless
+ it is certain that the destination mailbox can not be created, the
+ server MUST send the response code "[TRYCREATE]" as the prefix of
+ the text of the tagged NO response. This gives a hint to the
+ client that it can attempt a CREATE command and retry the COPY if
+ the CREATE is successful.
+
+ If the COPY command is unsuccessful for any reason, server
+ implementations MUST restore the destination mailbox to its state
+ before the COPY attempt.
+
+ Example: C: A003 COPY 2:4 MEETING
+ S: A003 OK COPY completed
+
+
+6.4.8. UID Command
+
+ Arguments: command name
+ command arguments
+
+ Responses: untagged responses: FETCH, SEARCH
+
+ Result: OK - UID command completed
+ NO - UID command error
+ BAD - command unknown or arguments invalid
+
+ The UID command has two forms. In the first form, it takes as its
+ arguments a COPY, FETCH, or STORE command with arguments
+ appropriate for the associated command. However, the numbers in
+ the sequence set argument are unique identifiers instead of
+ message sequence numbers. Sequence set ranges are permitted, but
+ there is no guarantee that unique identifiers will be contiguous.
+
+ A non-existent unique identifier is ignored without any error
+ message generated. Thus, it is possible for a UID FETCH command
+ to return an OK without any data or a UID COPY or UID STORE to
+ return an OK without performing any operations.
+
+ In the second form, the UID command takes a SEARCH command with
+ SEARCH command arguments. The interpretation of the arguments is
+ the same as with SEARCH; however, the numbers returned in a SEARCH
+ response for a UID SEARCH command are unique identifiers instead
+
+
+
+Crispin Standards Track [Page 60]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ of message sequence numbers. For example, the command UID SEARCH
+ 1:100 UID 443:557 returns the unique identifiers corresponding to
+ the intersection of two sequence sets, the message sequence number
+ range 1:100 and the UID range 443:557.
+
+ Note: in the above example, the UID range 443:557
+ appears. The same comment about a non-existent unique
+ identifier being ignored without any error message also
+ applies here. Hence, even if neither UID 443 or 557
+ exist, this range is valid and would include an existing
+ UID 495.
+
+ Also note that a UID range of 559:* always includes the
+ UID of the last message in the mailbox, even if 559 is
+ higher than any assigned UID value. This is because the
+ contents of a range are independent of the order of the
+ range endpoints. Thus, any UID range with * as one of
+ the endpoints indicates at least one message (the
+ message with the highest numbered UID), unless the
+ mailbox is empty.
+
+ The number after the "*" in an untagged FETCH response is always a
+ message sequence number, not a unique identifier, even for a UID
+ command response. However, server implementations MUST implicitly
+ include the UID message data item as part of any FETCH response
+ caused by a UID command, regardless of whether a UID was specified
+ as a message data item to the FETCH.
+
+
+ Note: The rule about including the UID message data item as part
+ of a FETCH response primarily applies to the UID FETCH and UID
+ STORE commands, including a UID FETCH command that does not
+ include UID as a message data item. Although it is unlikely that
+ the other UID commands will cause an untagged FETCH, this rule
+ applies to these commands as well.
+
+ Example: C: A999 UID FETCH 4827313:4828442 FLAGS
+ S: * 23 FETCH (FLAGS (\Seen) UID 4827313)
+ S: * 24 FETCH (FLAGS (\Seen) UID 4827943)
+ S: * 25 FETCH (FLAGS (\Seen) UID 4828442)
+ S: A999 OK UID FETCH completed
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 61]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+6.5. Client Commands - Experimental/Expansion
+
+
+6.5.1. X<atom> Command
+
+ Arguments: implementation defined
+
+ Responses: implementation defined
+
+ Result: OK - command completed
+ NO - failure
+ BAD - command unknown or arguments invalid
+
+ Any command prefixed with an X is an experimental command.
+ Commands which are not part of this specification, a standard or
+ standards-track revision of this specification, or an
+ IESG-approved experimental protocol, MUST use the X prefix.
+
+ Any added untagged responses issued by an experimental command
+ MUST also be prefixed with an X. Server implementations MUST NOT
+ send any such untagged responses, unless the client requested it
+ by issuing the associated experimental command.
+
+ Example: C: a441 CAPABILITY
+ S: * CAPABILITY IMAP4rev1 XPIG-LATIN
+ S: a441 OK CAPABILITY completed
+ C: A442 XPIG-LATIN
+ S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay
+ S: A442 OK XPIG-LATIN ompleted-cay
+
+7. Server Responses
+
+ Server responses are in three forms: status responses, server data,
+ and command continuation request. The information contained in a
+ server response, identified by "Contents:" in the response
+ descriptions below, is described by function, not by syntax. The
+ precise syntax of server responses is described in the Formal Syntax
+ section.
+
+ The client MUST be prepared to accept any response at all times.
+
+ Status responses can be tagged or untagged. Tagged status responses
+ indicate the completion result (OK, NO, or BAD status) of a client
+ command, and have a tag matching the command.
+
+ Some status responses, and all server data, are untagged. An
+ untagged response is indicated by the token "*" instead of a tag.
+ Untagged status responses indicate server greeting, or server status
+
+
+
+Crispin Standards Track [Page 62]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ that does not indicate the completion of a command (for example, an
+ impending system shutdown alert). For historical reasons, untagged
+ server data responses are also called "unsolicited data", although
+ strictly speaking, only unilateral server data is truly
+ "unsolicited".
+
+ Certain server data MUST be recorded by the client when it is
+ received; this is noted in the description of that data. Such data
+ conveys critical information which affects the interpretation of all
+ subsequent commands and responses (e.g., updates reflecting the
+ creation or destruction of messages).
+
+ Other server data SHOULD be recorded for later reference; if the
+ client does not need to record the data, or if recording the data has
+ no obvious purpose (e.g., a SEARCH response when no SEARCH command is
+ in progress), the data SHOULD be ignored.
+
+ An example of unilateral untagged server data occurs when the IMAP
+ connection is in the selected state. In the selected state, the
+ server checks the mailbox for new messages as part of command
+ execution. Normally, this is part of the execution of every command;
+ hence, a NOOP command suffices to check for new messages. If new
+ messages are found, the server sends untagged EXISTS and RECENT
+ responses reflecting the new size of the mailbox. Server
+ implementations that offer multiple simultaneous access to the same
+ mailbox SHOULD also send appropriate unilateral untagged FETCH and
+ EXPUNGE responses if another agent changes the state of any message
+ flags or expunges any messages.
+
+ Command continuation request responses use the token "+" instead of a
+ tag. These responses are sent by the server to indicate acceptance
+ of an incomplete client command and readiness for the remainder of
+ the command.
+
+7.1. Server Responses - Status Responses
+
+ Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD
+ can be tagged or untagged. PREAUTH and BYE are always untagged.
+
+ Status responses MAY include an OPTIONAL "response code". A response
+ code consists of data inside square brackets in the form of an atom,
+ possibly followed by a space and arguments. The response code
+ contains additional information or status codes for client software
+ beyond the OK/NO/BAD condition, and are defined when there is a
+ specific action that a client can take based upon the additional
+ information.
+
+
+
+
+
+Crispin Standards Track [Page 63]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ The currently defined response codes are:
+
+ ALERT
+
+ The human-readable text contains a special alert that MUST be
+ presented to the user in a fashion that calls the user's
+ attention to the message.
+
+ BADCHARSET
+
+ Optionally followed by a parenthesized list of charsets. A
+ SEARCH failed because the given charset is not supported by
+ this implementation. If the optional list of charsets is
+ given, this lists the charsets that are supported by this
+ implementation.
+
+ CAPABILITY
+
+ Followed by a list of capabilities. This can appear in the
+ initial OK or PREAUTH response to transmit an initial
+ capabilities list. This makes it unnecessary for a client to
+ send a separate CAPABILITY command if it recognizes this
+ response.
+
+ PARSE
+
+ The human-readable text represents an error in parsing the
+ [RFC-2822] header or [MIME-IMB] headers of a message in the
+ mailbox.
+
+ PERMANENTFLAGS
+
+ Followed by a parenthesized list of flags, indicates which of
+ the known flags the client can change permanently. Any flags
+ that are in the FLAGS untagged response, but not the
+ PERMANENTFLAGS list, can not be set permanently. If the client
+ attempts to STORE a flag that is not in the PERMANENTFLAGS
+ list, the server will either ignore the change or store the
+ state change for the remainder of the current session only.
+ The PERMANENTFLAGS list can also include the special flag \*,
+ which indicates that it is possible to create new keywords by
+ attempting to store those flags in the mailbox.
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 64]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ READ-ONLY
+
+ The mailbox is selected read-only, or its access while selected
+ has changed from read-write to read-only.
+
+ READ-WRITE
+
+ The mailbox is selected read-write, or its access while
+ selected has changed from read-only to read-write.
+
+ TRYCREATE
+
+ An APPEND or COPY attempt is failing because the target mailbox
+ does not exist (as opposed to some other reason). This is a
+ hint to the client that the operation can succeed if the
+ mailbox is first created by the CREATE command.
+
+ UIDNEXT
+
+ Followed by a decimal number, indicates the next unique
+ identifier value. Refer to section 2.3.1.1 for more
+ information.
+
+ UIDVALIDITY
+
+ Followed by a decimal number, indicates the unique identifier
+ validity value. Refer to section 2.3.1.1 for more information.
+
+ UNSEEN
+
+ Followed by a decimal number, indicates the number of the first
+ message without the \Seen flag set.
+
+ Additional response codes defined by particular client or server
+ implementations SHOULD be prefixed with an "X" until they are
+ added to a revision of this protocol. Client implementations
+ SHOULD ignore response codes that they do not recognize.
+
+7.1.1. OK Response
+
+ Contents: OPTIONAL response code
+ human-readable text
+
+ The OK response indicates an information message from the server.
+ When tagged, it indicates successful completion of the associated
+ command. The human-readable text MAY be presented to the user as
+ an information message. The untagged form indicates an
+
+
+
+
+Crispin Standards Track [Page 65]
+\f
+RFC 3501 IMAPv4 March 2003
+
+
+ information-only message; the nature of the information MAY be
+ indicated by a response code.
+
+ The untagged form is also used as one of three possible greetings
+ at connection startup. It indicates that the connection is not
+ yet authenticated and that a LOGIN command is needed.
+
+ Example: S: * OK IMAP4rev1 server ready
+ C: A001 LOGIN fred blurdybloop
+ S: * OK [ALERT] System shutdown in 10 minutes
+ S: A001 OK LOGIN Completed
+
+
+7.1.2. NO Response
+
+ Contents: OPTIONAL response code
+ human-readable text
+
+ The NO response indicates an operational error message from the
+ server. When tagged, it indicates unsuccessful completion of the
+ associated command. The untagged form indicates a warning; the
+ command can still complete successfully. The human-readable text
+ describes the condition.
+
+ Example: C: A222 COPY 1:2 owatagusiam
+ S: * NO Disk is 98% full, please delete unnecessary data
+ S: A222 OK COPY completed
+ C: A223 COPY 3:200 blurdybloop
+ S: * NO Disk is 98% full, please delete unnecessary data
+ S: * NO Disk is 99% full, please delete unnecessary data
+ S: A223 NO COPY failed: disk is full
+
+
+7.1.3. BAD Response
+
+ Contents: OPTIONAL
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