💾 Archived View for gemini.bortzmeyer.org › rfc-mirror › rfc1730.txt captured on 2022-01-08 at 19:53:01.
⬅️ Previous capture (2021-11-30)
-=-=-=-=-=-=-
Network Working Group M. Crispin
Request for Comments: 1730 University of Washington
Category: Standards Track December 1994
INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4
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 4 (IMAP4) allows a
client to access and manipulate electronic mail messages on a server.
IMAP4 permits manipulation of remote message folders, called
"mailboxes", in a way that is functionally equivalent to local
mailboxes. IMAP4 also provides the capability for an offline client
to resynchronize with the server (see also [IMAP-DISC]).
IMAP4 includes operations for creating, deleting, and renaming
mailboxes; checking for new messages; permanently removing messages;
setting and clearing flags; RFC 822 and MIME parsing; searching; and
selective fetching of message attributes, texts, and portions
thereof. Messages in IMAP4 are accessed by the use of numbers.
These numbers are either message sequence numbers (relative position
from 1 to the number of messages in the mailbox) or unique
identifiers (immutable, strictly ascending values assigned to each
message, but which are not necessarily contiguous).
IMAP4 supports a single server. A mechanism for supporting multiple
IMAP4 servers is discussed in [IMSP].
IMAP4 does not specify a means of posting mail; this function is
handled by a mail transfer protocol such as [SMTP].
IMAP4 is designed to be upwards compatible from the [IMAP2] protocol.
Compatibility issues are discussed in [IMAP-COMPAT].
Crispin [Page i]
RFC 1730 IMAP4 December 1994
Table of Contents
IMAP4 Protocol Specification ...................................... 1
1. Organization of this Document ............................. 1
1.1. How to Read This Document ................................. 1
1.2. Conventions Used in this Document ......................... 1
2. Protocol Overview ......................................... 1
2.1. Link Level ................................................ 1
2.2. Commands and Responses .................................... 1
2.2.1. Client Protocol Sender and Server Protocol Receiver ....... 2
2.2.2. Server Protocol Sender and Client Protocol Receiver ....... 2
3. State and Flow Diagram .................................... 4
3.1. Non-Authenticated State ................................... 4
3.2. Authenticated State ....................................... 4
3.3. Selected State ............................................ 4
3.4. Logout State .............................................. 4
4. Data Formats .............................................. 6
4.1. Atom ...................................................... 6
4.2. Number .................................................... 6
4.3. String .................................................... 6
4.3.1. 8-bit and Binary Strings .................................. 7
4.4. Parenthesized List ........................................ 7
4.5. NIL ....................................................... 7
5. Operational Considerations ................................ 8
5.1. Mailbox Naming ............................................ 8
5.2. Mailbox Size and Message Status Updates ................... 8
5.3. Response when no Command in Progress ...................... 8
5.4. Autologout Timer .......................................... 9
5.5. Multiple Commands in Progress ............................. 9
6. Client Commands ........................................... 10
6.1. Client Commands - Any State ............................... 10
6.1.1. CAPABILITY Command ........................................ 10
6.1.2. NOOP Command .............................................. 11
6.1.3. LOGOUT Command ............................................ 11
6.2. Client Commands - Non-Authenticated State ................. 12
6.2.1. AUTHENTICATE Command ...................................... 12
6.2.2. LOGIN Command ............................................. 14
6.3. Client Commands - Authenticated State ..................... 14
6.3.1. SELECT Command ............................................ 15
6.3.2. EXAMINE Command ........................................... 16
6.3.3. CREATE Command ............................................ 17
6.3.4. DELETE Command ............................................ 18
6.3.5. RENAME Command ............................................ 18
Crispin [Page ii]
RFC 1730 IMAP4 December 1994
6.3.6. SUBSCRIBE Command ......................................... 19
6.3.7. UNSUBSCRIBE Command ....................................... 19
6.3.8. LIST Command .............................................. 20
6.3.9. LSUB Command .............................................. 22
6.3.10. APPEND Command ............................................ 22
6.4. Client Commands - Selected State .......................... 23
6.4.1. CHECK Command ............................................. 23
6.4.2. CLOSE Command ............................................. 24
6.4.3. EXPUNGE Command ........................................... 25
6.4.4. SEARCH Command ............................................ 25
6.4.5. FETCH Command ............................................. 29
6.4.6. PARTIAL Command ........................................... 32
6.4.7. STORE Command ............................................. 33
6.4.8. COPY Command .............................................. 34
6.4.9. UID Command ............................................... 35
6.5. Client Commands - Experimental/Expansion .................. 37
6.5.1. X<atom> Command ........................................... 37
7. Server Responses .......................................... 38
7.1. Server Responses - Status Responses ....................... 39
7.1.1. OK Response ............................................... 40
7.1.2. NO Response ............................................... 40
7.1.3. BAD Response .............................................. 41
7.1.4. PREAUTH Response .......................................... 41
7.1.5. BYE Response .............................................. 41
7.2. Server Responses - Server and Mailbox Status .............. 42
7.2.1. CAPABILITY Response ....................................... 42
7.2.2. LIST Response ............................................. 43
7.2.3. LSUB Response ............................................. 44
7.2.4. SEARCH Response ........................................... 44
7.2.5. FLAGS Response ............................................ 44
7.3. Server Responses - Message Status ......................... 45
7.3.1. EXISTS Response ........................................... 45
7.3.2. RECENT Response ........................................... 45
7.3.3. EXPUNGE Response .......................................... 45
7.3.4. FETCH Response ............................................ 46
7.3.5. Obsolete Responses ........................................ 51
7.4. Server Responses - Command Continuation Request ........... 51
8. Sample IMAP4 session ...................................... 52
9. Formal Syntax ............................................. 53
10. Author's Note ............................................. 64
11. Security Considerations ................................... 64
12. Author's Address .......................................... 64
Appendices ........................................................ 65
A. Obsolete Commands ......................................... 65
A.6.3.OBS.1. FIND ALL.MAILBOXES Command ........................ 65
A.6.3.OBS.2. FIND MAILBOXES Command ............................ 65
A.6.3.OBS.3. SUBSCRIBE MAILBOX Command ......................... 66
A.6.3.OBS.4. UNSUBSCRIBE MAILBOX Command ....................... 66
Crispin [Page iii]
RFC 1730 IMAP4 December 1994
B. Obsolete Responses ........................................ 68
B.7.2.OBS.1. MAILBOX Response .................................. 68
B.7.3.OBS.1. COPY Response ..................................... 68
B.7.3.OBS.2. STORE Response .................................... 69
C. References ................................................ 70
E. IMAP4 Keyword Index ....................................... 71
Crispin [Page iv]
RFC 1730 IMAP4 December 1994
IMAP4 Protocol Specification
1. Organization of this Document
1.1. How to Read This Document
This document is written from the point of view of the implementor of
an IMAP4 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 IMAP4 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, one should not attempt to deduce command syntax from the
command section alone; one should 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.
2. Protocol Overview
2.1. Link Level
The IMAP4 protocol assumes a reliable data stream such as provided by
TCP. When TCP is used, an IMAP4 server listens on port 143.
2.2. Commands and Responses
An IMAP4 session consists of the establishment of a client/server
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 IMAP4 client or server is either reading a line, or is reading
a sequence of octets with a known count followed by a line.
Crispin [Page 1]
RFC 1730 IMAP4 December 1994
2.2.1. Client Protocol Sender and Server Protocol Receiver
The client command begins an operation. Each client command is
prefixed with a 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.
The protocol receiver of an IMAP4 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
Crispin [Page 2]
RFC 1730 IMAP4 December 1994
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 IMAP4 client reads a response line from
the server. It then takes action on the response based upon the
first token of the response, which may be a tag, a "*", or a "+". As
described above.
A client MUST be prepared to accept any server response at all times.
This includes server data that it may not have 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, recording the data is
mandatory.
This topic is discussed in greater detail in the Server Responses
section.
Crispin [Page 3]
RFC 1730 IMAP4 December 1994
3. State and Flow Diagram
An IMAP4 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 user 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 user 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.
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 session 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.
Crispin [Page 4]
RFC 1730 IMAP4 December 1994
+--------------------------------------+
|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
Crispin [Page 5]
RFC 1730 IMAP4 December 1994
4. Data Formats
IMAP4 uses textual commands and responses. Data in IMAP4 can be in
one of several forms: atom, number, string, parenthesized list, or
NIL.
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 restrictions of what may be 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 respresented 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 [Page 6]
RFC 1730 IMAP4 December 1994
4.3.1. 8-bit and Binary Strings
8-bit textual and binary mail is supported through the use of
[MIME-1] encoding. IMAP4 implementations MAY transmit 8-bit or
multi-octet characters in literals, but should do so only when the
character set 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, although this is not required.
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 may itself 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 ().
Crispin [Page 7]
RFC 1730 IMAP4 December 1994
5. Operational Considerations
5.1. Mailbox Naming
The interpretation of mailbox names is implementation-dependent.
However, the mailbox name INBOX is a special name reserved to mean
"the primary mailbox for this user on this server". 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.
5.2. 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 details.
Regardless of what implementation decisions a client may take 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.
Crispin [Page 8]
RFC 1730 IMAP4 December 1994
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.
5.5. Multiple Commands in Progress
The client is not required to wait for the completion result response
of a command before sending another command, subject to flow control
constraints on the underlying data stream. Similarly, a server is
not required to process a command to completion before beginning
processing of the next command, unless an ambiguity would result
because of a command that would affect the results of other commands.
If there is such an ambiguity, the server executes commands to
completion in the order given by the client.
Crispin [Page 9]
RFC 1730 IMAP4 December 1994
6. Client Commands
IMAP4 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 data to be returned; these are
identified by "Data:" 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 data 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
Data: mandatory 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 "IMAP4" as the first listed capability
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
session.
Crispin [Page 10]
RFC 1730 IMAP4 December 1994
Capability names other than "IMAP4" refer to extensions,
revisions, or amendments to this specification. See the
documentation of the CAPABILITY response for additional
information. No capabilities 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 IMAP4
S: abcd OK CAPABILITY completed
6.1.2. NOOP Command
Arguments: none
Data: no specific data 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
Crispin [Page 11]
RFC 1730 IMAP4 December 1994
6.1.3. LOGOUT Command
Arguments: none
Data: mandatory 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 session. 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 IMAP4 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.
Crispin [Page 12]
RFC 1730 IMAP4 December 1994
6.2.1. AUTHENTICATE Command
Arguments: authentication mechanism name
Data: continuation data may 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
user. Optionally, it also negotiates a 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 should issue 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 protocol session. 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.
The server is not required to support any particular
authentication mechanism, nor are authentication mechanisms
required to support any protection mechanisms. If an AUTHENTICATE
command fails with a NO response, the client may try another
Crispin [Page 13]
RFC 1730 IMAP4 December 1994
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 IMAP4 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
Data: no specific data 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 user 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.
Crispin [Page 14]
RFC 1730 IMAP4 December 1994
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,
and APPEND.
6.3.1. SELECT Command
Arguments: mailbox name
Data: mandatory 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
<n> EXISTS The number of messages in the mailbox
<n> RECENT The number of messages added to the mailbox since
the previous time this mailbox was read
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. If it
is not possible to determine the messages that were added since
the previous time a mailbox was read, then all messages SHOULD be
considered recent.
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 may change permanently.
Only one mailbox may be selected at a time in a session;
simultaneous access to multiple mailboxes requires multiple
Crispin [Page 15]
RFC 1730 IMAP4 December 1994
sessions. 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 user 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 user 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 user's .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
Data: mandatory 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.
Crispin [Page 16]
RFC 1730 IMAP4 December 1994
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
Data: no specific data 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 may, in the
future, create mailbox names under this name in the hierarchy.
Server implementations that do not require this declaration MUST
ignore it.
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
Crispin [Page 17]
RFC 1730 IMAP4 December 1994
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
Data: no specific data 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. Any error in deletion will
return a tagged NO response.
The value of the highest-used unique indentifier 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.
Example: C: A683 DELETE blurdybloop
S: A683 OK DELETE completed
6.3.5. RENAME Command
Arguments: existing mailbox name
new mailbox name
Data: no specific data 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
Crispin [Page 18]
RFC 1730 IMAP4 December 1994
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.
Renaming INBOX is permitted; a new, empty INBOX is created in its
place.
Example: C: Z4S9 RENAME blurdybloop owatagusiam
S: Z4S9 OK RENAME completed
6.3.6. SUBSCRIBE Command
Arguments: mailbox
Data: no specific data 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.
Example: C: A002 SUBSCRIBE #news.comp.mail.mime
S: A002 OK SUBSCRIBE completed
6.3.7. UNSUBSCRIBE Command
Arguments: mailbox name
Data: no specific data 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.
Crispin [Page 19]
RFC 1730 IMAP4 December 1994
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
Data: 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 user. 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.
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.
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.
Crispin [Page 20]
RFC 1730 IMAP4 December 1994
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 detail).
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 it
matches the input arguments and INBOX is supported by this server
for this user. 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: A002 LIST "~/Mail/" "%"
S: * LIST (\Noselect) "/" ~/Mail/foo
S: * LIST () "/" ~/Mail/meetings
S: A002 OK LIST completed
Crispin [Page 21]
RFC 1730 IMAP4 December 1994
6.3.9. LSUB Command
Arguments: reference name
mailbox name with possible wildcards
Data: 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.
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. APPEND Command
Arguments: mailbox name
optional flag parenthesized list
optional date/time string
message literal
Data: no specific data 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
in the specified destination mailbox. This argument is 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 [MIME-1] encoding.
If a flag parenthesized list or date_time are specified, that data
SHOULD be set in the resulting message; otherwise, the defaults of
empty flags and the current date/time are used.
Crispin [Page 22]
RFC 1730 IMAP4 December 1994
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 mailbox is currently selected, the
normal new mail actions should occur.
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.
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, FIND
ALL.MAILBOXES, FIND MAILBOXES, and APPEND), the following commands
are valid in the selected state: CHECK, CLOSE, EXPUNGE, SEARCH,
FETCH, PARTIAL, STORE, COPY, and UID.
Crispin [Page 23]
RFC 1730 IMAP4 December 1994
6.4.1. CHECK Command
Arguments: none
Data: no specific data 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
Data: no specific data 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 when a mailbox is selected, it is not required to send a
CLOSE command before a SELECT, EXAMINE, or LOGOUT command. The
SELECT, EXAMINE, and LOGOUT commands implicitly close the
currently selected mailbox without doing an expunge. However,
Crispin [Page 24]
RFC 1730 IMAP4 December 1994
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
6.4.3. EXPUNGE Command
Arguments: none
Data: 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.
Crispin [Page 25]
RFC 1730 IMAP4 December 1994
6.4.4. SEARCH Command
Arguments: optional character set specification
searching criteria (one or more)
Data: mandatory untagged response: SEARCH
Result: OK - search completed
NO - search error: can't search that character set 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.
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 may 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-1] body parts with
terminal content types other than TEXT and MESSAGE from
consideration in SEARCH matching.
The optional character set specification consists of the word
"CHARSET" followed by a registered MIME character set. It
indicates the character set of the strings that appear in the
search criteria. [MIME-2] strings that appear in RFC 822/MIME
message headers, and [MIME-1] content transfer encodings, MUST be
decoded before matching. Except for US-ASCII, it is not required
that any particular character set be supported. If the server
does not support the specified character set, 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.
Crispin [Page 26]
RFC 1730 IMAP4 December 1994
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.
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 RFC822.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 [Page 27]
RFC 1730 IMAP4 December 1994
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.
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 RFC822.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.
Crispin [Page 28]
RFC 1730 IMAP4 December 1994
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.
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
Data: 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 may 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>]
The text of a particular body section. The section
specification is a set of one or more part numbers
delimited by periods.
Single-part messages only have a part 1.
Crispin [Page 29]
RFC 1730 IMAP4 December 1994
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.
It is not permitted to fetch a multipart part
itself, only its individual members.
A part of type MESSAGE and subtype RFC822 also has
nested parts. These are the parts of the MESSAGE
part's body. Nested part 0 of a part of type
MESSAGE and subtype RFC822 is the [RFC-822] header
of the message.
Every message has at least one part.
Here is an example of a complex message
with its associated section
specifications:
0 ([RFC-822] header of the message)
MULTIPART/MIXED
1 TEXT/PLAIN
2 APPLICATION/OCTET-STREAM
3 MESSAGE/RFC822
3.0 ([RFC-822] header of the message)
3.1 TEXT/PLAIN
3.2 APPLICATION/OCTET-STREAM
MULTIPART/MIXED
4.1 IMAGE/GIF
4.2 MESSAGE/RFC822
4.2.0 ([RFC-822] header of the message)
4.2.1 TEXT/PLAIN
MULTIPART/ALTERNATIVE
4.2.2.1 TEXT/PLAIN
4.2.2.2 TEXT/RICHTEXT
Note that there is no section
specification for the Multi-part parts
(no section 4 or 4.2.2).
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>]
An alternate form of BODY[section] that does not
implicitly set the \Seen flag.
Crispin [Page 30]
RFC 1730 IMAP4 December 1994
BODYSTRUCTURE The [MIME-1] body structure of the message. This
is computed by the server by parsing the [MIME-1]
header lines.
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 date and time of final delivery of the message
as defined by RFC 821.
RFC822 The message in [RFC-822] format. The \Seen flag is
implicitly set; if this causes the flags to change
they should be included as part of the fetch
responses. This is the concatenation of
RFC822.HEADER and RFC822.TEXT.
RFC822.PEEK An alternate form of RFC822 that does not
implicitly set the \Seen flag.
RFC822.HEADER The [RFC-822] format header of the message as
stored on the server including the delimiting blank
line between the header and the body.
RFC822.HEADER.LINES <header_list>
All header lines (including continuation lines) of
the [RFC-822] format header of the message with a
field-name (as defined in [RFC-822]) that matches
any of the strings in header_list. The matching is
case-insensitive but otherwise exact. The
delimiting blank line between the header and the
body is always included.
Crispin [Page 31]
RFC 1730 IMAP4 December 1994
RFC822.HEADER.LINES.NOT <header_list>
All header lines (including continuation lines) of
the [RFC-822] format header of the message with a
field-name (as defined in [RFC-822]) that does not
match any of the strings in header_list. The
matching is case-insensitive but otherwise exact.
The delimiting blank line between the header and
the body is always included.
RFC822.SIZE The number of octets in the message, as expressed
in [RFC-822] format.
RFC822.TEXT The text body of the message, omitting the
[RFC-822] header. The \Seen flag is implicitly
set; if this causes the flags to change they should
be included as part of the fetch responses.
RFC822.TEXT.PEEK
An alternate form of RFC822.TEXT that does not
implicitly set the \Seen flag.
UID The unique identifier for the message.
Example: C: A654 FETCH 2:4 (FLAGS RFC822.HEADER.LINES (DATE FROM))
S: * 2 FETCH ....
S: * 3 FETCH ....
S: * 4 FETCH ....
S: A003 OK FETCH completed
6.4.6. PARTIAL Command
Arguments: message sequence number
message data item name
position of first octet
number of octets
Data: untagged responses: FETCH
Result: OK - partial completed
NO - partial error: can't fetch that data
BAD - command unknown or arguments invalid
The PARTIAL command is equivalent to the associated FETCH command,
with the added functionality that only the specified number of
octets, beginning at the specified starting octet, are returned.
Only a single message can be fetched at a time. The first octet
Crispin [Page 32]
RFC 1730 IMAP4 December 1994
of a message, and hence the minimum for the starting octet, is
octet 1.
The following FETCH items are valid data for PARTIAL: RFC822,
RFC822.HEADER, RFC822.TEXT, BODY[section], as well as any .PEEK
forms of these.
Any partial fetch that attempts to read beyond the end of the text
is truncated as appropriate. If the starting octet is beyond the
end of the text, an empty string is returned.
The data are returned with the FETCH response. There is no
indication of the range of the partial data in this response. It
is not possible to stream multiple PARTIAL commands of the same
data item without processing and synchronizing at each step, since
streamed commands may be executed out of order.
There is no requirement that partial fetches follow any sequence.
For example, if a partial fetch of octets 1 through 10000 breaks
in an awkward place for BASE64 decoding, it is permitted to
continue with a partial fetch of 9987 through 19987, etc.
The handling of the \Seen flag is the same as in the associated
FETCH command.
Example: C: A005 PARTIAL 4 RFC822 1 1024
S: * 1 FETCH (RFC822 {1024}
S: Return-Path: <gray@cac.washington.edu>
S: ...
S: ......... FLAGS (\Seen))
S: A005 OK PARTIAL completed
6.4.7. STORE Command
Arguments: message set
message data item name
value for message data item
Data: 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
Crispin [Page 33]
RFC 1730 IMAP4 December 1994
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.
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.
+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
Crispin [Page 34]
RFC 1730 IMAP4 December 1994
6.4.8. COPY Command
Arguments: message set
mailbox name
Data: no specific data 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 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.
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
6.4.9. UID Command
Arguments: command name
command arguments
Data: 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.
Crispin [Page 35]
RFC 1730 IMAP4 December 1994
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.
A unique identifier of a message is a number, and is guaranteed
not to refer to any other message in the mailbox. Unique
identifiers are assigned in a strictly ascending fashion for each
message added to the mailbox. Unlike message sequence numbers,
unique identifiers 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 message selection time. If unique
identifiers from an earlier session fail to persist to this
session, the unique identifier validity value MUST be greater than
in the earlier session.
Note: An example of a good value to use for the unique
identifier validity value would be 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 identifers will never be
reused, even in the case of a mailbox being deleted and
a new mailbox by the same name created at some future
time.
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 UID was specified
as a message data item to the FETCH.
Crispin [Page 36]
RFC 1730 IMAP4 December 1994
Example: C: A003 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
Data: 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, or a standard
or standards-track revision of this specification, 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 IMAP4 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
Crispin [Page 37]
RFC 1730 IMAP4 December 1994
7. Server Responses
Server responses are in three forms: status responses, server data,
and command continuation request.
Server response data, identified by "Data:" in the response
descriptions below, are described by function, not by syntax. The
precise syntax of server response data is described in the Formal
Syntax section.
The client MUST be prepared to accept any response at all times.
Status responses that are tagged indicate the completion result 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 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 messags).
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 responses occurs when the IMAP
connection is in selected state. In selected state, the server
checks the mailbox for new messages as part of the execution of each
command. 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.
Crispin [Page 38]
RFC 1730 IMAP4 December 1994
7.1. Server Responses - Status Responses
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.
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.
PARSE The human-readable text represents an error in
parsing the [RFC-822] or [MIME-1] headers of a
message in the mailbox.
PERMANENTFLAGS Followed by a parenthesized list of flags,
indicates which of the known flags that the client
may 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 may 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.
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 may succeed if the mailbox is first
created by the CREATE command.
Crispin [Page 39]
RFC 1730 IMAP4 December 1994
UIDVALIDITY Followed by a decimal number, indicates the unique
identifier validity value. See the description of
the UID command for more detail.
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
Data: 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 session startup. It indicates that the session is not yet
authenticated and that a LOGIN command is needed.
Example: S: * OK IMAP4 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
Data: 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 may still complete successfully. The human-readable text
describes the condition.
Crispin [Page 40]
RFC 1730 IMAP4 December 1994
Example: C: A222 COPY 1:2 owatagusiam
S: * NO Disk is 98% full, please delete unnecessary data
S: A222 OK COPY completed
C: A222 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: A222 NO COPY failed: disk is full
7.1.3. BAD Response
Data: 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 may 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
Data: optional response code
human-readable text
The PREAUTH response is always untagged, and is one of three
possible greetings at session startup. It indicates that the
session has already been authenticated by external means and thus
no LOGIN command is needed.
Example: S: * PREAUTH IMAP4 server ready and logged in as Smith
Crispin [Page 41]
RFC 1730 IMAP4 December 1994
7.1.5. BYE Response
Data: optional response code
human-readable text
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 may be sent as part of a normal logout sequence, or as a
panic shutdown announcement by the server. It is also used by
some server implementations as an announcement of an inactivity
autologout.
This response is also used as one of three possible greetings at
session startup. It indicates that the server is not willing to
accept a session from this client.
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 data are
transmitted from the server to the client, often as a result of a
command with the same name.
7.2.1. CAPABILITY Response
Data: 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 first
name in the capability listing MUST be the atom "IMAP4".
A capability name other than IMAP4 indicates that the server
supports an extension, revision, or amendment to the IMAP4
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 IMAP4 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".
Crispin [Page 42]
RFC 1730 IMAP4 December 1994
Client implementations SHOULD NOT require any capability name
other than "IMAP4", and MUST ignore any unknown capability names.
Example: S: * CAPABILITY IMAP4 XPIG-LATIN
7.2.2. LIST Response
Data: 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
may 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.
The hierarchy delimiter is a character used to delimit levels of
hierarchy in a mailbox name. A client may 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.
Crispin [Page 43]
RFC 1730 IMAP4 December 1994
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
Data: 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
may 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. SEARCH Response
Data: zero or more numbers
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
7.2.5. FLAGS Response
Data: 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 may 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)
Crispin [Page 44]
RFC 1730 IMAP4 December 1994
7.3. 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 either a message sequence number or a message
count.
7.3.1. EXISTS Response
Data: 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
7.3.2. RECENT Response
Data: none
The RECENT response reports the number of messages that have
arrived since the previous time a SELECT command was done on this
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 RECENT response MUST be recorded by the
client.
Example: S: * 5 RECENT
7.3.3. EXPUNGE Response
Data: 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).
Crispin [Page 45]
RFC 1730 IMAP4 December 1994
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
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
7.3.4. FETCH Response
Data: 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] 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.
8-bit textual data is permitted if a character set
identifier is part of the body parameter
parenthesized list for this section.
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
Crispin [Page 46]
RFC 1730 IMAP4 December 1994
original binary data, the client must decode the
transfer encoded string.
BODYSTRUCTURE A parenthesized list that describes the body
structure of a message. This is computed by the
server by parsing the [RFC-822] header and body
into the component parts, defaulting various fields
as necessary.
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.).
Extension data follows the multipart subtype.
Extension data is never returned with the BODY
fetch, but may 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 "baz"] as
defined in [MIME-1].
Any following extension data are not yet defined in
this version of the protocol. Such extension data
may 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 type name as defined
in [MIME-1].
Crispin [Page 47]
RFC 1730 IMAP4 December 1994
body subtype
A string giving the content subtype name as
defined in [MIME-1].
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-1].
body id
A string giving the content id as defined in
[MIME-1].
body description
A string giving the content description as
defined in [MIME-1].
body encoding
A string giving the content transfer encoding as
defined in [MIME-1].
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
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 may 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:
Crispin [Page 48]
RFC 1730 IMAP4 December 1994
body MD5
A string giving the content MD5 value as defined
in [MIME-1].
Any following extension data are not yet defined in
this version of the protocol, and would be as
described above under multipart extension data.
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.
Crispin [Page 49]
RFC 1730 IMAP4 December 1994
FLAGS A parenthesized list of flags that are set for this
message. This may include keywords as well as the
following system flags:
\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).
as well as the following special flag, which may be
fetched but not stored:
\Recent Message has arrived since the previous
time this mailbox was selected.
INTERNALDATE A string containing the date and time of final
delivery of the message as defined by [SMTP].
RFC822 A string expressing the message in [RFC-822]
format. The header portion of the message must be
7-bit. 8-bit characters are permitted only in the
non-header portion of the message only if there are
[MIME-1] data in the message that identify the
character set of the message.
RFC822.HEADER A string expressing the [RFC-822] format header of
the message, including the delimiting blank line
between the header and the body. The entire string
must be 7-bit; 8-bit characters are not permitted
in headers. RFC822.HEADER is used to return data
for the RFC822.HEADER, RFC822.HEADER.LINES, and
RFC822.HEADER.LINES.NOT FETCH data items. Note
that a blank line is always included regardless of
header line restrictions.
RFC822.SIZE A number expressing the number of octets in the
message in [RFC-822] format.
Crispin [Page 50]
RFC 1730 IMAP4 December 1994
RFC822.TEXT A string expressing the text body of the message,
omitting the [RFC-822] header. 8-bit characters
are permitted only if there are [MIME-1] data in
the message that identify the character set of the
message.
UID A number expressing the unique identifier of the
message.
Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827)
7.3.5. Obsolete Responses
In addition to the responses listed in here, client implementations
MUST accept and implement the obsolete responses described in
Appendix B.
7.4. Server Responses - Command Continuation Request
The command completion 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"
Crispin [Page 51]
RFC 1730 IMAP4 December 1994
8. Sample IMAP4 session
The following is a transcript of an IMAP4 session. A long line in
this sample is broken for editorial clarity.
S: * OK IMAP4 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
S: a002 OK [READ-WRITE] SELECT completed
C: a003 fetch 12 full
S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "14-Jul-1993 02:44:25 -0700"
RFC822.SIZE 4282 ENVELOPE ("Wed, 14 Jul 1993 02:23:25 -0700 (PDT)"
"IMAP4 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 rfc822.header
S: * 12 FETCH (RFC822.HEADER {346}
S: Date: Wed, 14 Jul 1993 02:23:25 -0700 (PDT)
S: From: Terry Gray <gray@cac.washington.edu>
S: Subject: IMAP4 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 IMAP4 server terminating connection
S: a006 OK LOGOUT completed
Crispin [Page 52]
RFC 1730 IMAP4 December 1994
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 a comma.
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.
Syntax marked as obsolete may be encountered with implementations
written for an earlier version of this protocol (e.g. IMAP2). New
implementations SHOULD accept obsolete syntax as input, but MUST NOT
otherwise use such syntax.
address ::= "(" addr_name SPACE addr_adl SPACE addr_mailbox
SPACE addr_host ")"
addr_adl ::= nstring
addr_host ::= nstring
;; NIL indicates [RFC-822] group syntax
addr_mailbox ::= nstring
;; NIL indicates end of [RFC-822] group; if
;; non-NIL and addr_host is NIL, holds
;; [RFC-822] group name
addr_name ::= nstring
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
Crispin [Page 53]
RFC 1730 IMAP4 December 1994
atom ::= 1*ATOM_CHAR
ATOM_CHAR ::= <any CHAR except atom_specials>
atom_specials ::= "(" / ")" / "{" / SPACE / CTLs / list_wildcards /
quoted_specials
authenticate ::= "AUTHENTICATE" SPACE auth_type *(CRLF base64)
auth_type ::= atom
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 1#body_extension]
;; MUST NOT be returned on non-extensible
;; "BODY" fetch
body_ext_mpart ::= body_fld_param [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_enc ::= (<"> ("7BIT" / "8BIT" / "BINARY" / "BASE64"/
"QUOTED-PRINTABLE") <">) / string
body_fld_id ::= nstring
body_fld_lines ::= number
Crispin [Page 54]
RFC 1730 IMAP4 December 1994
body_fld_md5 ::= nstring
body_fld_octets ::= number
body_fld_param ::= "(" 1#(string string) ")" / nil
body_fld_subtyp ::= string
body_type_1part ::= (body_type_basic / body_type_msg / body_type_text)
[SPACE body_ext_1part]
body_type_basic ::= (<"> ("APPLICATION" / "AUDIO" / "IMAGE" /
"MESSAGE" / "VIDEO") <">) / string) SPACE
body_fld_subtyp SPACE body_fields
;; MESSAGE subtype MUST NOT be "RFC822"
body_type_mpart ::= 1*body SPACE body_fld_subtyp
[SPACE body_ext_mpart]
body_type_msg ::= <"> "MESSAGE" <"> SPACE <"> "RFC822" <"> SPACE
body_fields SPACE envelope SPACE body SPACE
body_fld_lines
body_type_text ::= <"> "TEXT" <"> SPACE body_fld_subtyp SPACE
body_fields SPACE body_fld_lines
capability ::= atom
;; Must begin with "X" or be registered with
;; IANA as standard or standards-track
capability_data ::= "CAPABILITY" SPACE "IMAP4" [SPACE 1#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 / find / list /
lsub / rename / select / subscribe / unsubscribe /
;; Valid only in Authenticated or Selected state
Crispin [Page 55]
RFC 1730 IMAP4 December 1994
command_nonauth ::= login / authenticate
;; Valid only when in Non-Authenticated state
command_select ::= "CHECK" / "CLOSE" / "EXPUNGE" /
copy / fetch / partial / 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, 0x0C>
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_old)
date_year ::= 4digit
date_year_old ::= 2digit
;; OBSOLETE, (year - 1900)
date_time ::= <"> (date_time_new / date_time_old) <">
date_time_new ::= date_day_fixed "-" date_month "-" date_year
SPACE time SPACE zone
date_time_old ::= date_day_fixed "-" date_month "-" date_year_old
SPACE time "-" zone_old
;; OBSOLETE
Crispin [Page 56]
RFC 1730 IMAP4 December 1994
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"
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 ::= "BODY" / "BODYSTRUCTURE" /
"BODY" [".PEEK"] "[" section "]" / "ENVELOPE" /
"FLAGS" / "INTERNALDATE" / "UID" /
"RFC822" (([".TEXT"] [".PEEK"]) / ".SIZE" /
(".HEADER" [".LINES" [".NOT"] SPACE header_list])
find ::= "FIND" SPACE ["ALL."] "MAILBOXES" SPACE
list_mailbox
;; OBSOLETE
Crispin [Page 57]
RFC 1730 IMAP4 December 1994
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
flag_list ::= "(" #flag ")"
greeting ::= "*" SPACE (resp_cond_auth / resp_cond_bye) CRLF
header_line ::= astring
header_list ::= "(" 1#header_line ")"
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; other names may be
;; case-sensitive depending on implementation.
mailbox_data ::= "FLAGS" SPACE flag_list /
"LIST" SPACE mailbox_list /
"LSUB" SPACE mailbox_list /
"MAILBOX" SPACE text /
"SEARCH" [SPACE 1#nz_number] /
number SPACE "EXISTS" / number SPACE "RECENT"
Crispin [Page 58]
RFC 1730 IMAP4 December 1994
mailbox_list ::= "(" #("\Marked" / "\Noinferiors" /
"\Noselect" / "\Unmarked" / flag_extension) ")"
SPACE (<"> QUOTED_CHAR <"> / nil) SPACE mailbox
message_data ::= nz_number SPACE ("EXPUNGE" /
("FETCH" SPACE msg_fetch) / msg_obsolete)
msg_fetch ::= "(" 1#("BODY" SPACE body /
"BODYSTRUCTURE" SPACE body /
"BODY[" section "]" SPACE nstring /
"ENVELOPE" SPACE envelope /
"FLAGS" SPACE "(" #(flag / "\Recent") ")" /
"INTERNALDATE" SPACE date_time /
"RFC822" [".HEADER" / ".TEXT"] SPACE nstring /
"RFC822.SIZE" SPACE number /
"UID" SPACE uniqueid) ")"
msg_obsolete ::= "COPY" / ("STORE" SPACE msg_fetch)
;; OBSOLETE untagged data responses
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)
partial ::= "PARTIAL" SPACE nz_number SPACE
("BODY" [".PEEK"] "[" section "]" /
"RFC822" (([".TEXT"] [".PEEK"]) / ".HEADER")
SPACE number SPACE number
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
Crispin [Page 59]
RFC 1730 IMAP4 December 1994
response ::= *response_data response_done
response_data ::= "*" SPACE (resp_cond_state / resp_cond_bye /
mailbox_data / message_data / capability_data)
CRLF
response_done ::= response_tagged / response_fatal
response_fatal ::= "*" SPACE resp_cond_bye CRLF
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
;; Server will disconnect condition
resp_cond_state ::= ("OK" / "NO" / "BAD") SPACE resp_text
;; Status condition
resp_text ::= ["[" resp_text_code "]" SPACE] (text_mime2 / text)
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]
search_criteria
;; Character set must be registered with IANA
;; as a MIME character set
search_criteria ::= 1#search_key
search_key ::= search_new / search_old
search_new ::= "DRAFT" /
"HEADER" SPACE header_line 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 /
"UID" SPACE set / "UNDRAFT" / set /
"(" search_criteria ")"
;; New in IMAP4
Crispin [Page 60]
RFC 1730 IMAP4 December 1994
search_old ::= "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"
;; Defined in [IMAP2]
section ::= "0" / nz_number ["." section]
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>
store ::= "STORE" SPACE set SPACE store_att_flags
store_att_flags ::= (["+" / "-"] "FLAGS" [".SILENT"]) SPACE
(flag_list / #flag)
string ::= quoted / literal
subscribe ::= ("SUBSCRIBE" SPACE mailbox) / subscribe_obs
subscribe_obs ::= "SUBSCRIBE" SPACE "MAILBOX" SPACE mailbox
;;OBSOLETE
Crispin [Page 61]
RFC 1730 IMAP4 December 1994
tag ::= 1*<any ATOM_CHAR except "+">
text ::= 1*TEXT_CHAR
text_mime2 ::= "=?" <charset> "?" <encoding> "?"
<encoded-text> "?="
;; Syntax defined in [MIME-2]
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) / unsubscribe_obs
unsubscribe_obs ::= "UNSUBSCRIBE" SPACE "MAILBOX" SPACE mailbox
;;OBSOLETE
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".
Crispin [Page 62]
RFC 1730 IMAP4 December 1994
zone_old ::= "UT" / "GMT" / "Z" / ;; +0000
"AST" / "EDT" / ;; -0400
"EST" / "CDT" / ;; -0500
"CST" / "MDT" / ;; -0600
"MST" / "PDT" / ;; -0700
"PST" / "YDT" / ;; -0800
"YST" / "HDT" / ;; -0900
"HST" / "BDT" / ;; -1000
"BST" / ;; -1100
"A" / "B" / "C" / "D" / "E" / "F" / ;; +1 to +6
"G" / "H" / "I" / "K" / "L" / "M" / ;; +7 to +12
"N" / "O" / "P" / "Q" / "R" / "S" / ;; -1 to -6
"T" / "U" / "V" / "W" / "X" / "Y" ;; -7 to -12
;; OBSOLETE
Crispin [Page 63]
RFC 1730 IMAP4 December 1994
10. Author's Note
This document is a revision or rewrite of earlier documents, and
supercedes the protocol specification in those documents: IMAP4
Internet drafts, the IMAP2bis Internet drafts, unpublished
IMAP2bis.TXT document, RFC 1176, and RFC 1064.
11. Security Considerations
IMAP4 protocol transactions, including electronic mail data, are sent
in the clear over the network unless the optional 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.
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, JE-30
University of Washington
Seattle, WA 98195
Phone: (206) 543-5762
EMail: MRC@CAC.Washington.EDU
Crispin [Page 64]
RFC 1730 IMAP4 December 1994
Appendices
A. Obsolete Commands
The following commands are OBSOLETE. It is NOT required to support
any of these commands in new server implementations. These commands
are documented here for the benefit of implementors who may wish to
support them for compatibility with old client implementations.
The section headings of these commands are intended to correspond
with where they would be located in the main document if they were
not obsoleted.
A.6.3.OBS.1. FIND ALL.MAILBOXES Command
Arguments: mailbox name with possible wildcards
Data: untagged responses: MAILBOX
Result: OK - find completed
NO - find failure: can't list that name
BAD - command unknown or arguments invalid
The FIND ALL.MAILBOXES command returns a subset of names from the
complete set of all names available to the user. It returns zero
or more untagged MAILBOX replies. The mailbox argument to FIND
ALL.MAILBOXES is similar to that for LIST with an empty reference,
except that the characters "%" and "?" match a single character.
Example: C: A002 FIND ALL.MAILBOXES *
S: * MAILBOX blurdybloop
S: * MAILBOX INBOX
S: A002 OK FIND ALL.MAILBOXES completed
A.6.3.OBS.2. FIND MAILBOXES Command
Arguments: mailbox name with possible wildcards
Data: untagged responses: MAILBOX
Result: OK - find completed
NO - find failure: can't list that name
BAD - command unknown or arguments invalid
The FIND MAILBOXES command returns a subset of names from the set
of names that the user has declared as being "active" or
Crispin [Page 65]
RFC 1730 IMAP4 December 1994
"subscribed". It returns zero or more untagged MAILBOX replies.
The mailbox argument to FIND MAILBOXES is similar to that for LSUB
with an empty reference, except that the characters "%" and "?"
match a single character.
Example: C: A002 FIND MAILBOXES *
S: * MAILBOX blurdybloop
S: * MAILBOX INBOX
S: A002 OK FIND MAILBOXES completed
A.6.3.OBS.3. SUBSCRIBE MAILBOX Command
Arguments: mailbox name
Data: no specific data for this command
Result: OK - subscribe completed
NO - subscribe failure: can't subscribe to that name
BAD - command unknown or arguments invalid
The SUBSCRIBE MAILBOX command is identical in effect to the
SUBSCRIBE command. A server which implements this command must be
able to distinguish between a SUBSCRIBE MAILBOX command and a
SUBSCRIBE command with a mailbox name argument of "MAILBOX".
Example: C: A002 SUBSCRIBE MAILBOX #news.comp.mail.mime
S: A002 OK SUBSCRIBE MAILBOX to #news.comp.mail.mime
completed
C: A003 SUBSCRIBE MAILBOX
S: A003 OK SUBSCRIBE to MAILBOX completed
A.6.3.OBS.4. UNSUBSCRIBE MAILBOX Command
Arguments: mailbox name
Data: no specific data for this command
Result: OK - unsubscribe completed
NO - unsubscribe failure: can't unsubscribe that name
BAD - command unknown or arguments invalid
The UNSUBSCRIBE MAILBOX command is identical in effect to the
UNSUBSCRIBE command. A server which implements this command must
be able to distinguish between a UNSUBSCRIBE MAILBOX command and
an UNSUBSCRIBE command with a mailbox name argument of "MAILBOX".
Crispin [Page 66]
RFC 1730 IMAP4 December 1994
Example: C: A002 UNSUBSCRIBE MAILBOX #news.comp.mail.mime
S: A002 OK UNSUBSCRIBE MAILBOX from #news.comp.mail.mime
completed
C: A003 UNSUBSCRIBE MAILBOX
S: A003 OK UNSUBSCRIBE from MAILBOX completed
Crispin [Page 67]
RFC 1730 IMAP4 December 1994
B. Obsolete Responses
The following responses are OBSOLETE. Except as noted below, these
responses MUST NOT be transmitted by new server implementations.
The section headings of these responses are intended to correspond
with where they would be located in the main document if they were
not obsoleted.
B.7.2.OBS.1. MAILBOX Response
Data: name
The MAILBOX response MUST NOT be transmitted by server
implementations except in response to the obsolete FIND MAILBOXES
and FIND ALL.MAILBOXES commands. Client implementations that do
not use these commands MAY ignore this response. It is documented
here for the benefit of implementors who may wish to support it
for compatibility with old client implementations.
This response occurs as a result of the FIND MAILBOXES and FIND
ALL.MAILBOXES commands. It returns a single name that matches the
FIND specification. There are no attributes or hierarchy
delimiter.
Example: S: * MAILBOX blurdybloop
B.7.3.OBS.1. COPY Response
Data: none
The COPY response MUST NOT be transmitted by new server
implementations. Client implementations MUST ignore the COPY
response. It is documented here for the benefit of client
implementors who may encounter this response from old server
implementations.
In some experimental versions of this protocol, this response was
returned in response to a COPY command to indicate on a
per-message basis that the message was copied successfully.
Example: S: * 44 COPY
Crispin [Page 68]
RFC 1730 IMAP4 December 1994
B.7.3.OBS.2. STORE Response
Data: message data
The STORE response MUST NOT be transmitted by new server
implementations. Client implementations MUST treat the STORE
response as equivalent to the FETCH response. It is documented
here for the benefit of client implementors who may encounter this
response from old server implementations.
In some experimental versions of this protocol, this response was
returned instead of FETCH in response to a STORE command to report
the new value of the flags.
Example: S: * 69 STORE (FLAGS (\Deleted))
Crispin [Page 69]
RFC 1730 IMAP4 December 1994
C. References
[IMAP-AUTH] Myers, J., "IMAP4 Authentication Mechanism", RFC 1731.
Carnegie-Mellon University, December 1994.
[IMAP-COMPAT] Crispin, M. "IMAP4 Compatibility with IMAP2 and
IMAP2bis", RFC 1732, University of Washington, December 1994.
[IMAP-DISC] Austein, R. "Synchronization Operations for Disconnected
IMAP4 Clients", Work in Progress.
[IMAP-MODEL] Crispin, M. "Distributed Electronic Mail Models in
IMAP4", RFC 1733, University of Washington, December 1994.
[IMAP-NAMING] Crispin, M. "Mailbox Naming Convention in IMAP4", Work
in Progress.
[IMAP2] Crispin, M., "Interactive Mail Access Protocol - Version 2",
RFC 1176, University of Washington, August 1990.
[IMSP] Myers, J. "IMSP -- Internet Message Support Protocol", Work in
Progress.
[MIME-1] Borenstein, N., and Freed, N., "MIME (Multipurpose Internet
Mail Extensions) Part One: Mechanisms for Specifying and Describing
the Format of Internet Message Bodies", RFC 1521, Bellcore, Innosoft,
September 1993.
[MIME-2] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
Part Two: Message Header Extensions for Non-ASCII Text", RFC 1522,
University of Tennessee, September 1993.
[RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", STD 11, RFC 822, University of Delaware, August 1982.
[SMTP] Postel, Jonathan B. "Simple Mail Transfer Protocol", STD 10,
RFC 821, USC/Information Sciences Institute, August 1982.
Crispin [Page 70]
RFC 1730 IMAP4 December 1994
E. IMAP4 Keyword Index
+FLAGS <flag list> (store command data item) ............... 34
+FLAGS.SILENT <flag list> (store command data item) ........ 34
-FLAGS <flag list> (store command data item) ............... 34
-FLAGS.SILENT <flag list> (store command data item) ........ 34
ALERT (response code) ...................................... 39
ALL (fetch item) ........................................... 29
ALL (search key) ........................................... 27
ANSWERED (search key) ...................................... 27
APPEND (command) ........................................... 22
AUTHENTICATE (command) ..................................... 12
BAD (response) ............................................. 41
BCC <string> (search key) .................................. 27
BEFORE <date> (search key) ................................. 27
BODY (fetch item) .......................................... 29
BODY (fetch result) ........................................ 46
BODY <string> (search key) ................................. 27
BODY.PEEK[<section>] (fetch item) .......................... 30
BODYSTRUCTURE (fetch item) ................................. 31
BODYSTRUCTURE (fetch result) ............................... 47
BODY[<section>] (fetch item) ............................... 29
BODY[section] (fetch result) ............................... 46
BYE (response) ............................................. 41
CAPABILITY (command) ....................................... 10
CAPABILITY (response) ...................................... 42
CC <string> (search key) ................................... 27
CHECK (command) ............................................ 23
CLOSE (command) ............................................ 24
COPY (command) ............................................. 34
COPY (response) ............................................ 68
CREATE (command) ........................................... 17
DELETE (command) ........................................... 18
DELETED (search key) ....................................... 27
DRAFT (search key) ......................................... 27
ENVELOPE (fetch item) ...................................... 31
ENVELOPE (fetch result) .................................... 49
EXAMINE (command) .......................................... 16
EXISTS (response) .......................................... 45
EXPUNGE (command) .......................................... 25
EXPUNGE (response) ......................................... 45
FAST (fetch item) .......................................... 31
FETCH (command) ............................................ 29
FETCH (response) ........................................... 46
FIND ALL.MAILBOXES (command) ............................... 65
FIND MAILBOXES (command) ................................... 65
FLAGGED (search key) ....................................... 27
FLAGS (fetch item) ......................................... 31
Crispin [Page 71]
RFC 1730 IMAP4 December 1994
FLAGS (fetch result) ....................................... 50
FLAGS (response) ........................................... 44
FLAGS <flag list> (store command data item) ................ 34
FLAGS.SILENT <flag list> (store command data item) ......... 34
FROM <string> (search key) ................................. 27
FULL (fetch item) .......................................... 31
HEADER <field-name> <string> (search key) .................. 27
INTERNALDATE (fetch item) .................................. 31
INTERNALDATE (fetch result) ................................ 50
KEYWORD <flag> (search key) ................................ 27
LARGER <n> (search key) .................................... 27
LIST (command) ............................................. 20
LIST (response) ............................................ 43
LOGIN (command) ............................................ 14
LOGOUT (command) ........................................... 11
LSUB (command) ............................................. 22
LSUB (response) ............................................ 44
MAILBOX (response) ......................................... 68
NEW (search key) ........................................... 27
NO (response) .............................................. 40
NOOP (command) ............................................. 11
NOT <search-key> (search key) .............................. 28
OK (response) .............................................. 40
OLD (search key) ........................................... 28
ON <date> (search key) ..................................... 28
OR <search-key1> <search-key2> (search key) ................ 28
PARSE (response code) ...................................... 39
PARTIAL (command) .......................................... 32
PERMANENTFLAGS (response code) ............................. 39
PREAUTH (response) ......................................... 41
READ-ONLY (response code) .................................. 39
READ-WRITE (response code) ................................. 39
RECENT (response) .......................................... 45
RECENT (search key) ........................................ 28
RENAME (command) ........................................... 18
RFC822 (fetch item) ........................................ 31
RFC822 (fetch result) ...................................... 50
RFC822.HEADER (fetch item) ................................. 31
RFC822.HEADER (fetch result) ............................... 50
RFC822.HEADER.LINES <header_list> (fetch item) ............. 31
RFC822.HEADER.LINES.NOT <header_list> (fetch item) ......... 32
RFC822.PEEK (fetch item) ................................... 31
RFC822.SIZE (fetch item) ................................... 32
RFC822.SIZE (fetch result) ................................. 50
RFC822.TEXT (fetch item) ................................... 32
RFC822.TEXT (fetch result) ................................. 51
RFC822.TEXT.PEEK (fetch item) .............................. 32
SEARCH (command) ........................................... 25
Crispin [Page 72]
RFC 1730 IMAP4 December 1994
SEARCH (response) .......................................... 44
SEEN (search key) .......................................... 28
SELECT (command) ........................................... 15
SENTBEFORE <date> (search key) ............................. 28
SENTON <date> (search key) ................................. 28
SENTSINCE <date> (search key) .............................. 28
SINCE <date> (search key) .................................. 28
SMALLER <n> (search key) ................................... 28
STORE (command) ............................................ 33
STORE (response) ........................................... 69
SUBJECT <string> (search key) .............................. 28
SUBSCRIBE (command) ........................................ 19
SUBSCRIBE MAILBOX (command) ................................ 66
TEXT <string> (search key) ................................. 28
TO <string> (search key) ................................... 28
TRYCREATE (response code) .................................. 39
UID (command) .............................................. 35
UID (fetch item) ........................................... 32
UID (fetch result) ......................................... 51
UID <message set> (search key) ............................. 28
UIDVALIDITY (response code) ................................ 40
UNANSWERED (search key) .................................... 29
UNDELETED (search key) ..................................... 29
UNDRAFT (search key) ....................................... 29
UNFLAGGED (search key) ..................................... 29
UNKEYWORD <flag> (search key) .............................. 29
UNSEEN (response code) ..................................... 40
UNSEEN (search key) ........................................ 29
UNSUBSCRIBE (command) ...................................... 19
UNSUBSCRIBE MAILBOX (command) .............................. 66
X<atom> (command) .......................................... 37
\Answered (system flag) .................................... 50
\Deleted (system flag) ..................................... 50
\Draft (system flag) ....................................... 50
\Flagged (system flag) ..................................... 50
\Marked (mailbox name attribute) ........................... 43
\Noinferiors (mailbox name attribute) ...................... 43
\Noselect (mailbox name attribute) ......................... 43
\Recent (system flag) ...................................... 50
\Seen (system flag) ........................................ 50
\Unmarked (mailbox name attribute) ......................... 43
Crispin [Page 73]