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RFC 2060

 
 
 

Internet Message Access Protocol - Version 4rev1

Part 3 of 3, p. 48 to 82
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7.      Server Responses

   Server responses are in three forms: status responses, server data,
   and command continuation request.  The information contained in a
   server response, identified by "Contents:" in the response
   descriptions below, is described by function, not by syntax.  The
   precise syntax of server responses is described in the Formal Syntax
   section.

   The client MUST be prepared to accept any response at all times.

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   Status responses can be tagged or untagged.  Tagged status responses
   indicate the completion result (OK, NO, or BAD status) of a client
   command, and have a tag matching the command.

   Some status responses, and all server data, are untagged.  An
   untagged response is indicated by the token "*" instead of a tag.
   Untagged status responses indicate server greeting, or server status
   that does not indicate the completion of a command (for example, an
   impending system shutdown alert).  For historical reasons, untagged
   server data responses are also called "unsolicited data", although
   strictly speaking only unilateral server data is truly "unsolicited".

   Certain server data MUST be recorded by the client when it is
   received; this is noted in the description of that data.  Such data
   conveys critical information which affects the interpretation of all
   subsequent commands and responses (e.g. updates reflecting the
   creation or destruction of messages).

   Other server data SHOULD be recorded for later reference; if the
   client does not need to record the data, or if recording the data has
   no obvious purpose (e.g. a SEARCH response when no SEARCH command is
   in progress), the data SHOULD be ignored.

   An example of unilateral untagged server data occurs when the IMAP
   connection is in selected state.  In selected state, the server
   checks the mailbox for new messages as part of command execution.
   Normally, this is part of the execution of every command; hence, a
   NOOP command suffices to check for new messages.  If new messages are
   found, the server sends untagged EXISTS and RECENT responses
   reflecting the new size of the mailbox.  Server implementations that
   offer multiple simultaneous access to the same mailbox SHOULD also
   send appropriate unilateral untagged FETCH and EXPUNGE responses if
   another agent changes the state of any message flags or expunges any
   messages.

   Command continuation request responses use the token "+" instead of a
   tag.  These responses are sent by the server to indicate acceptance
   of an incomplete client command and readiness for the remainder of
   the command.

7.1.    Server Responses - Status Responses

   Status responses are OK, NO, BAD, PREAUTH and BYE.  OK, NO, and BAD
   may be tagged or untagged.  PREAUTH and BYE are always untagged.

   Status responses MAY include an OPTIONAL "response code".  A response
   code consists of data inside square brackets in the form of an atom,
   possibly followed by a space and arguments.  The response code

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   contains additional information or status codes for client software
   beyond the OK/NO/BAD condition, and are defined when there is a
   specific action that a client can take based upon the additional
   information.

   The currently defined response codes are:

      ALERT          The human-readable text contains a special alert
                     that MUST be presented to the user in a fashion
                     that calls the user's attention to the message.

      NEWNAME        Followed by a mailbox name and a new mailbox name.
                     A SELECT or EXAMINE is failing because the target
                     mailbox name no longer exists because it was
                     renamed to the new mailbox name.  This is a hint to
                     the client that the operation can succeed if the
                     SELECT or EXAMINE is reissued with the new mailbox
                     name.

      PARSE          The human-readable text represents an error in
                     parsing the [RFC-822] header or [MIME-IMB] headers
                     of a message in the mailbox.

      PERMANENTFLAGS Followed by a parenthesized list of flags,
                     indicates which of the known flags that the client
                     can change permanently.  Any flags that are in the
                     FLAGS untagged response, but not the PERMANENTFLAGS
                     list, can not be set permanently.  If the client
                     attempts to STORE a flag that is not in the
                     PERMANENTFLAGS list, the server will either reject
                     it with a NO reply or store the state for the
                     remainder of the current session only.  The
                     PERMANENTFLAGS list can also include the special
                     flag \*, which indicates that it is possible to
                     create new keywords by attempting to store those
                     flags in the mailbox.

      READ-ONLY      The mailbox is selected read-only, or its access
                     while selected has changed from read-write to
                     read-only.

      READ-WRITE     The mailbox is selected read-write, or its access
                     while selected has changed from read-only to
                     read-write.

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      TRYCREATE      An APPEND or COPY attempt is failing because the
                     target mailbox does not exist (as opposed to some
                     other reason).  This is a hint to the client that
                     the operation can succeed if the mailbox is first
                     created by the CREATE command.

      UIDVALIDITY    Followed by a decimal number, indicates the unique
                     identifier validity value.

      UNSEEN         Followed by a decimal number, indicates the number
                     of the first message without the \Seen flag set.

      Additional response codes defined by particular client or server
      implementations SHOULD be prefixed with an "X" until they are
      added to a revision of this protocol.  Client implementations
      SHOULD ignore response codes that they do not recognize.

7.1.1.  OK Response

   Contents:   OPTIONAL response code
               human-readable text

      The OK response indicates an information message from the server.
      When tagged, it indicates successful completion of the associated
      command.  The human-readable text MAY be presented to the user as
      an information message.  The untagged form indicates an
      information-only message; the nature of the information MAY be
      indicated by a response code.

      The untagged form is also used as one of three possible greetings
      at connection startup.  It indicates that the connection is not
      yet authenticated and that a LOGIN command is needed.

   Example:    S: * OK IMAP4rev1 server ready
               C: A001 LOGIN fred blurdybloop
               S: * OK [ALERT] System shutdown in 10 minutes
               S: A001 OK LOGIN Completed

7.1.2.  NO Response

      Contents:   OPTIONAL response code
                  human-readable text

      The NO response indicates an operational error message from the
      server.  When tagged, it indicates unsuccessful completion of the
      associated command.  The untagged form indicates a warning; the
      command can still complete successfully.  The human-readable text
      describes the condition.

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   Example:    C: A222 COPY 1:2 owatagusiam
               S: * NO Disk is 98% full, please delete unnecessary data
               S: A222 OK COPY completed
               C: A223 COPY 3:200 blurdybloop
               S: * NO Disk is 98% full, please delete unnecessary data
               S: * NO Disk is 99% full, please delete unnecessary data
               S: A223 NO COPY failed: disk is full

7.1.3.  BAD Response

   Contents:   OPTIONAL response code
               human-readable text

      The BAD response indicates an error message from the server.  When
      tagged, it reports a protocol-level error in the client's command;
      the tag indicates the command that caused the error.  The untagged
      form indicates a protocol-level error for which the associated
      command can not be determined; it can also indicate an internal
      server failure.  The human-readable text describes the condition.

   Example:    C: ...very long command line...
               S: * BAD Command line too long
               C: ...empty line...
               S: * BAD Empty command line
               C: A443 EXPUNGE
               S: * BAD Disk crash, attempting salvage to a new disk!
               S: * OK Salvage successful, no data lost
               S: A443 OK Expunge completed

7.1.4.  PREAUTH Response

   Contents:   OPTIONAL response code
               human-readable text

      The PREAUTH response is always untagged, and is one of three
      possible greetings at connection startup.  It indicates that the
      connection has already been authenticated by external means and
      thus no LOGIN command is needed.

   Example:    S: * PREAUTH IMAP4rev1 server logged in as Smith

7.1.5.  BYE Response

   Contents:   OPTIONAL response code
               human-readable text

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      The BYE response is always untagged, and indicates that the server
      is about to close the connection.  The human-readable text MAY be
      displayed to the user in a status report by the client.  The BYE
      response is sent under one of four conditions:

         1) as part of a normal logout sequence.  The server will close
            the connection after sending the tagged OK response to the
            LOGOUT command.

         2) as a panic shutdown announcement.  The server closes the
            connection immediately.

         3) as an announcement of an inactivity autologout.  The server
            closes the connection immediately.

         4) as one of three possible greetings at connection startup,
            indicating that the server is not willing to accept a
            connection from this client.  The server closes the
            connection immediately.

      The difference between a BYE that occurs as part of a normal
      LOGOUT sequence (the first case) and a BYE that occurs because of
      a failure (the other three cases) is that the connection closes
      immediately in the failure case.

   Example:    S: * BYE Autologout; idle for too long

7.2.    Server Responses - Server and Mailbox Status

   These responses are always untagged.  This is how server and mailbox
   status data are transmitted from the server to the client.  Many of
   these responses typically result from a command with the same name.

7.2.1.  CAPABILITY Response

   Contents:   capability listing

      The CAPABILITY response occurs as a result of a CAPABILITY
      command.  The capability listing contains a space-separated
      listing of capability names that the server supports.  The
      capability listing MUST include the atom "IMAP4rev1".

      A capability name which begins with "AUTH=" indicates that the
      server supports that particular authentication mechanism.

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      Other capability names indicate that the server supports an
      extension, revision, or amendment to the IMAP4rev1 protocol.
      Server responses MUST conform to this document until the client
      issues a command that uses the associated capability.

      Capability names MUST either begin with "X" or be standard or
      standards-track IMAP4rev1 extensions, revisions, or amendments
      registered with IANA.  A server MUST NOT offer unregistered or
      non-standard capability names, unless such names are prefixed with
      an "X".

      Client implementations SHOULD NOT require any capability name
      other than "IMAP4rev1", and MUST ignore any unknown capability
      names.

   Example:    S: * CAPABILITY IMAP4rev1 AUTH=KERBEROS_V4 XPIG-LATIN

7.2.2.  LIST Response

   Contents:   name attributes
               hierarchy delimiter
               name

      The LIST response occurs as a result of a LIST command.  It
      returns a single name that matches the LIST specification.  There
      can be multiple LIST responses for a single LIST command.

      Four name attributes are defined:

      \Noinferiors   It is not possible for any child levels of
                     hierarchy to exist under this name; no child levels
                     exist now and none can be created in the future.

      \Noselect      It is not possible to use this name as a selectable
                     mailbox.

      \Marked        The mailbox has been marked "interesting" by the
                     server; the mailbox probably contains messages that
                     have been added since the last time the mailbox was
                     selected.

      \Unmarked      The mailbox does not contain any additional
                     messages since the last time the mailbox was
                     selected.

      If it is not feasible for the server to determine whether the
      mailbox is "interesting" or not, or if the name is a \Noselect
      name, the server SHOULD NOT send either \Marked or \Unmarked.

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      The hierarchy delimiter is a character used to delimit levels of
      hierarchy in a mailbox name.  A client can use it to create child
      mailboxes, and to search higher or lower levels of naming
      hierarchy.  All children of a top-level hierarchy node MUST use
      the same separator character.  A NIL hierarchy delimiter means
      that no hierarchy exists; the name is a "flat" name.

      The name represents an unambiguous left-to-right hierarchy, and
      MUST be valid for use as a reference in LIST and LSUB commands.
      Unless \Noselect is indicated, the name MUST also be valid as an
            argument for commands, such as SELECT, that accept mailbox
      names.

   Example:    S: * LIST (\Noselect) "/" ~/Mail/foo

7.2.3.  LSUB Response

   Contents:   name attributes
               hierarchy delimiter
               name

      The LSUB response occurs as a result of an LSUB command.  It
      returns a single name that matches the LSUB specification.  There
      can be multiple LSUB responses for a single LSUB command.  The
      data is identical in format to the LIST response.

   Example:    S: * LSUB () "." #news.comp.mail.misc

7.2.4   STATUS Response

   Contents:   name
               status parenthesized list

      The STATUS response occurs as a result of an STATUS command.  It
      returns the mailbox name that matches the STATUS specification and
      the requested mailbox status information.

   Example:    S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292)

7.2.5.  SEARCH Response

   Contents:   zero or more numbers

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      The SEARCH response occurs as a result of a SEARCH or UID SEARCH
      command.  The number(s) refer to those messages that match the
      search criteria.  For SEARCH, these are message sequence numbers;
      for UID SEARCH, these are unique identifiers.  Each number is
      delimited by a space.

   Example:    S: * SEARCH 2 3 6

7.2.6.  FLAGS Response

   Contents:   flag parenthesized list

      The FLAGS response occurs as a result of a SELECT or EXAMINE
      command.  The flag parenthesized list identifies the flags (at a
      minimum, the system-defined flags) that are applicable for this
      mailbox.  Flags other than the system flags can also exist,
      depending on server implementation.

      The update from the FLAGS response MUST be recorded by the client.

   Example:    S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)

7.3.    Server Responses - Mailbox Size

   These responses are always untagged.  This is how changes in the size
   of the mailbox are trasnmitted from the server to the client.
   Immediately following the "*" token is a number that represents a
   message count.

7.3.1.  EXISTS Response

   Contents:   none

      The EXISTS response reports the number of messages in the mailbox.
      This response occurs as a result of a SELECT or EXAMINE command,
      and if the size of the mailbox changes (e.g. new mail).

      The update from the EXISTS response MUST be recorded by the
      client.

   Example:    S: * 23 EXISTS

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7.3.2.  RECENT Response

      Contents:   none

      The RECENT response reports the number of messages with the
      \Recent flag set.  This response occurs as a result of a SELECT or
      EXAMINE command, and if the size of the mailbox changes (e.g. new
      mail).

         Note: It is not guaranteed that the message sequence numbers of
         recent messages will be a contiguous range of the highest n
         messages in the mailbox (where n is the value reported by the
         RECENT response).  Examples of situations in which this is not
         the case are: multiple clients having the same mailbox open
         (the first session to be notified will see it as recent, others
         will probably see it as non-recent), and when the mailbox is
         re-ordered by a non-IMAP agent.

         The only reliable way to identify recent messages is to look at
         message flags to see which have the \Recent flag set, or to do
         a SEARCH RECENT.

         The update from the RECENT response MUST be recorded by the
         client.

   Example:    S: * 5 RECENT

7.4.    Server Responses - Message Status

   These responses are always untagged.  This is how message data are
   transmitted from the server to the client, often as a result of a
   command with the same name.  Immediately following the "*" token is a
   number that represents a message sequence number.

7.4.1.  EXPUNGE Response

   Contents:   none

      The EXPUNGE response reports that the specified message sequence
      number has been permanently removed from the mailbox.  The message
      sequence number for each successive message in the mailbox is
      immediately decremented by 1, and this decrement is reflected in
      message sequence numbers in subsequent responses (including other
      untagged EXPUNGE responses).

      As a result of the immediate decrement rule, message sequence
      numbers that appear in a set of successive EXPUNGE responses
      depend upon whether the messages are removed starting from lower

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      numbers to higher numbers, or from higher numbers to lower
      numbers.  For example, if the last 5 messages in a 9-message
      mailbox are expunged; a "lower to higher" server will send five
      untagged EXPUNGE responses for message sequence number 5, whereas
      a "higher to lower server" will send successive untagged EXPUNGE
      responses for message sequence numbers 9, 8, 7, 6, and 5.

      An EXPUNGE response MUST NOT be sent when no command is in
      progress; nor while responding to a FETCH, STORE, or SEARCH
      command.  This rule is necessary to prevent a loss of
      synchronization of message sequence numbers between client and
      server.

      The update from the EXPUNGE response MUST be recorded by the
      client.

   Example:    S: * 44 EXPUNGE

7.4.2.  FETCH Response

   Contents:   message data

      The FETCH response returns data about a message to the client.
      The data are pairs of data item names and their values in
      parentheses.  This response occurs as the result of a FETCH or
      STORE command, as well as by unilateral server decision (e.g. flag
      updates).

      The current data items are:

      BODY           A form of BODYSTRUCTURE without extension data.

      BODY[<section>]<<origin_octet>>
                     A string expressing the body contents of the
                     specified section.  The string SHOULD be
                     interpreted by the client according to the content
                     transfer encoding, body type, and subtype.

                     If the origin octet is specified, this string is a
                     substring of the entire body contents, starting at
                     that origin octet.  This means that BODY[]<0> MAY
                     be truncated, but BODY[] is NEVER truncated.

                     8-bit textual data is permitted if a [CHARSET]
                     identifier is part of the body parameter
                     parenthesized list for this section.  Note that
                     headers (part specifiers HEADER or MIME, or the
                     header portion of a MESSAGE/RFC822 part), MUST be

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                     7-bit; 8-bit characters are not permitted in
                     headers.  Note also that the blank line at the end
                     of the header is always included in header data.

                     Non-textual data such as binary data MUST be
                     transfer encoded into a textual form such as BASE64
                     prior to being sent to the client.  To derive the
                     original binary data, the client MUST decode the
                     transfer encoded string.

      BODYSTRUCTURE  A parenthesized list that describes the [MIME-IMB]
                     body structure of a message.  This is computed by
                     the server by parsing the [MIME-IMB] header fields,
                     defaulting various fields as necessary.

                     For example, a simple text message of 48 lines and
                     2279 octets can have a body structure of: ("TEXT"
                     "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 2279
                     48)

                     Multiple parts are indicated by parenthesis
                     nesting.  Instead of a body type as the first
                     element of the parenthesized list there is a nested
                     body.  The second element of the parenthesized list
                     is the multipart subtype (mixed, digest, parallel,
                     alternative, etc.).

                     For example, a two part message consisting of a
                     text and a BASE645-encoded text attachment can have
                     a body structure of: (("TEXT" "PLAIN" ("CHARSET"
                     "US-ASCII") NIL NIL "7BIT" 1152 23)("TEXT" "PLAIN"
                     ("CHARSET" "US-ASCII" "NAME" "cc.diff")
                     "<960723163407.20117h@cac.washington.edu>"
                     "Compiler diff" "BASE64" 4554 73) "MIXED"))

                     Extension data follows the multipart subtype.
                     Extension data is never returned with the BODY
                     fetch, but can be returned with a BODYSTRUCTURE
                     fetch.  Extension data, if present, MUST be in the
                     defined order.

                     The extension data of a multipart body part are in
                     the following order:

                     body parameter parenthesized list
                        A parenthesized list of attribute/value pairs
                        [e.g. ("foo" "bar" "baz" "rag") where "bar" is
                        the value of "foo" and "rag" is the value of

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                        "baz"] as defined in [MIME-IMB].

                     body disposition
                        A parenthesized list, consisting of a
                        disposition type string followed by a
                        parenthesized list of disposition
                        attribute/value pairs.  The disposition type and
                        attribute names will be defined in a future
                        standards-track revision to [DISPOSITION].

                     body language
                        A string or parenthesized list giving the body
                        language value as defined in [LANGUAGE-TAGS].

                     Any following extension data are not yet defined in
                     this version of the protocol.  Such extension data
                     can consist of zero or more NILs, strings, numbers,
                     or potentially nested parenthesized lists of such
                     data.  Client implementations that do a
                     BODYSTRUCTURE fetch MUST be prepared to accept such
                     extension data.  Server implementations MUST NOT
                     send such extension data until it has been defined
                     by a revision of this protocol.

                     The basic fields of a non-multipart body part are
                     in the following order:

                     body type
                        A string giving the content media type name as
                        defined in [MIME-IMB].

                     body subtype
                        A string giving the content subtype name as
                        defined in [MIME-IMB].

                     body parameter parenthesized list
                        A parenthesized list of attribute/value pairs
                        [e.g. ("foo" "bar" "baz" "rag") where "bar" is
                        the value of "foo" and "rag" is the value of
                        "baz"] as defined in [MIME-IMB].

                     body id
                        A string giving the content id as defined in
                        [MIME-IMB].

                     body description
                        A string giving the content description as
                        defined in [MIME-IMB].

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                     body encoding
                        A string giving the content transfer encoding as
                        defined in [MIME-IMB].

                     body size
                        A number giving the size of the body in octets.
                        Note that this size is the size in its transfer
                        encoding and not the resulting size after any
                        decoding.

                     A body type of type MESSAGE and subtype RFC822
                     contains, immediately after the basic fields, the
                     envelope structure, body structure, and size in
                     text lines of the encapsulated message.

                     A body type of type TEXT contains, immediately
                     after the basic fields, the size of the body in
                     text lines.  Note that this size is the size in its
                     content transfer encoding and not the resulting
                     size after any decoding.

                     Extension data follows the basic fields and the
                     type-specific fields listed above.  Extension data
                     is never returned with the BODY fetch, but can be
                     returned with a BODYSTRUCTURE fetch.  Extension
                     data, if present, MUST be in the defined order.

                     The extension data of a non-multipart body part are
                     in the following order:

                     body MD5
                        A string giving the body MD5 value as defined in
                        [MD5].

                     body disposition
                        A parenthesized list with the same content and
                        function as the body disposition for a multipart
                        body part.

                     body language
                        A string or parenthesized list giving the body
                        language value as defined in [LANGUAGE-TAGS].

                     Any following extension data are not yet defined in
                     this version of the protocol, and would be as
                     described above under multipart extension data.

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      ENVELOPE       A parenthesized list that describes the envelope
                     structure of a message.  This is computed by the
                     server by parsing the [RFC-822] header into the
                     component parts, defaulting various fields as
                     necessary.

                     The fields of the envelope structure are in the
                     following order: date, subject, from, sender,
                     reply-to, to, cc, bcc, in-reply-to, and message-id.
                     The date, subject, in-reply-to, and message-id
                     fields are strings.  The from, sender, reply-to,
                     to, cc, and bcc fields are parenthesized lists of
                     address structures.

                     An address structure is a parenthesized list that
                     describes an electronic mail address.  The fields
                     of an address structure are in the following order:
                     personal name, [SMTP] at-domain-list (source
                     route), mailbox name, and host name.

                     [RFC-822] group syntax is indicated by a special
                     form of address structure in which the host name
                     field is NIL.  If the mailbox name field is also
                     NIL, this is an end of group marker (semi-colon in
                     RFC 822 syntax).  If the mailbox name field is
                     non-NIL, this is a start of group marker, and the
                     mailbox name field holds the group name phrase.

                     Any field of an envelope or address structure that
                     is not applicable is presented as NIL.  Note that
                     the server MUST default the reply-to and sender
                     fields from the from field; a client is not
                     expected to know to do this.

      FLAGS          A parenthesized list of flags that are set for this
                     message.

      INTERNALDATE   A string representing the internal date of the
                     message.

      RFC822         Equivalent to BODY[].

      RFC822.HEADER  Equivalent to BODY.PEEK[HEADER].

      RFC822.SIZE    A number expressing the [RFC-822] size of the
                     message.

      RFC822.TEXT    Equivalent to BODY[TEXT].

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      UID            A number expressing the unique identifier of the
                     message.


   Example:    S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827)

7.5.    Server Responses - Command Continuation Request

   The command continuation request response is indicated by a "+" token
   instead of a tag.  This form of response indicates that the server is
   ready to accept the continuation of a command from the client.  The
   remainder of this response is a line of text.

   This response is used in the AUTHORIZATION command to transmit server
   data to the client, and request additional client data.  This
   response is also used if an argument to any command is a literal.

   The client is not permitted to send the octets of the literal unless
   the server indicates that it expects it.  This permits the server to
   process commands and reject errors on a line-by-line basis.  The
   remainder of the command, including the CRLF that terminates a
   command, follows the octets of the literal.  If there are any
   additional command arguments the literal octets are followed by a
   space and those arguments.

   Example:    C: A001 LOGIN {11}
               S: + Ready for additional command text
               C: FRED FOOBAR {7}
               S: + Ready for additional command text
               C: fat man
               S: A001 OK LOGIN completed
               C: A044 BLURDYBLOOP {102856}
               S: A044 BAD No such command as "BLURDYBLOOP"

8.      Sample IMAP4rev1 connection

   The following is a transcript of an IMAP4rev1 connection.  A long
   line in this sample is broken for editorial clarity.

S:   * OK IMAP4rev1 Service Ready
C:   a001 login mrc secret
S:   a001 OK LOGIN completed
C:   a002 select inbox
S:   * 18 EXISTS
S:   * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
S:   * 2 RECENT
S:   * OK [UNSEEN 17] Message 17 is the first unseen message
S:   * OK [UIDVALIDITY 3857529045] UIDs valid

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S:   a002 OK [READ-WRITE] SELECT completed
C:   a003 fetch 12 full
S:   * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700"
      RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)"
      "IMAP4rev1 WG mtg summary and minutes"
      (("Terry Gray" NIL "gray" "cac.washington.edu"))
      (("Terry Gray" NIL "gray" "cac.washington.edu"))
      (("Terry Gray" NIL "gray" "cac.washington.edu"))
      ((NIL NIL "imap" "cac.washington.edu"))
      ((NIL NIL "minutes" "CNRI.Reston.VA.US")
      ("John Klensin" NIL "KLENSIN" "INFOODS.MIT.EDU")) NIL NIL
      "<B27397-0100000@cac.washington.edu>")
       BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 92))
S:    a003 OK FETCH completed
C:    a004 fetch 12 body[header]
S:    * 12 FETCH (BODY[HEADER] {350}
S:    Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT)
S:    From: Terry Gray <gray@cac.washington.edu>
S:    Subject: IMAP4rev1 WG mtg summary and minutes
S:    To: imap@cac.washington.edu
S:    cc: minutes@CNRI.Reston.VA.US, John Klensin <KLENSIN@INFOODS.MIT.EDU>
S:    Message-Id: <B27397-0100000@cac.washington.edu>
S:    MIME-Version: 1.0
S:    Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
S:
S:    )
S:    a004 OK FETCH completed
C:    a005 store 12 +flags \deleted
S:    * 12 FETCH (FLAGS (\Seen \Deleted))
S:    a005 OK +FLAGS completed
C:    a006 logout
S:    * BYE IMAP4rev1 server terminating connection
S:    a006 OK LOGOUT completed

9.      Formal Syntax

   The following syntax specification uses the augmented Backus-Naur
   Form (BNF) notation as specified in [RFC-822] with one exception; the
   delimiter used with the "#" construct is a single space (SPACE) and
   not one or more commas.

   In the case of alternative or optional rules in which a later rule
   overlaps an earlier rule, the rule which is listed earlier MUST take
   priority.  For example, "\Seen" when parsed as a flag is the \Seen
   flag name and not a flag_extension, even though "\Seen" could be
   parsed as a flag_extension.  Some, but not all, instances of this
   rule are noted below.

Top      Up      ToC       Page 65 
   Except as noted otherwise, all alphabetic characters are case-
   insensitive.  The use of upper or lower case characters to define
   token strings is for editorial clarity only.  Implementations MUST
   accept these strings in a case-insensitive fashion.

address         ::= "(" addr_name SPACE addr_adl SPACE addr_mailbox
                    SPACE addr_host ")"

addr_adl        ::= nstring
                    ;; Holds route from [RFC-822] route-addr if
                    ;; non-NIL

addr_host       ::= nstring
                    ;; NIL indicates [RFC-822] group syntax.
                    ;; Otherwise, holds [RFC-822] domain name

addr_mailbox    ::= nstring
                    ;; NIL indicates end of [RFC-822] group; if
                    ;; non-NIL and addr_host is NIL, holds
                    ;; [RFC-822] group name.
                    ;; Otherwise, holds [RFC-822] local-part

addr_name       ::= nstring
                    ;; Holds phrase from [RFC-822] mailbox if
                    ;; non-NIL

alpha           ::= "A" / "B" / "C" / "D" / "E" / "F" / "G" / "H" /
                    "I" / "J" / "K" / "L" / "M" / "N" / "O" / "P" /
                    "Q" / "R" / "S" / "T" / "U" / "V" / "W" / "X" /
                    "Y" / "Z" /
                    "a" / "b" / "c" / "d" / "e" / "f" / "g" / "h" /
                    "i" / "j" / "k" / "l" / "m" / "n" / "o" / "p" /
                    "q" / "r" / "s" / "t" / "u" / "v" / "w" / "x" /
                    "y" / "z"
                    ;; Case-sensitive

append          ::= "APPEND" SPACE mailbox [SPACE flag_list]
                    [SPACE date_time] SPACE literal

astring         ::= atom / string

atom            ::= 1*ATOM_CHAR

ATOM_CHAR       ::= <any CHAR except atom_specials>

atom_specials   ::= "(" / ")" / "{" / SPACE / CTL / list_wildcards /
                    quoted_specials

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authenticate    ::= "AUTHENTICATE" SPACE auth_type *(CRLF base64)

auth_type       ::= atom
                    ;; Defined by [IMAP-AUTH]

base64          ::= *(4base64_char) [base64_terminal]

base64_char     ::= alpha / digit / "+" / "/"

base64_terminal ::= (2base64_char "==") / (3base64_char "=")

body            ::= "(" body_type_1part / body_type_mpart ")"

body_extension  ::= nstring / number / "(" 1#body_extension ")"
                    ;; Future expansion.  Client implementations
                    ;; MUST accept body_extension fields.  Server
                    ;; implementations MUST NOT generate
                    ;; body_extension fields except as defined by
                    ;; future standard or standards-track
                    ;; revisions of this specification.

body_ext_1part  ::= body_fld_md5 [SPACE body_fld_dsp
                    [SPACE body_fld_lang
                    [SPACE 1#body_extension]]]
                    ;; MUST NOT be returned on non-extensible
                    ;; "BODY" fetch

body_ext_mpart  ::= body_fld_param
                    [SPACE body_fld_dsp SPACE body_fld_lang
                    [SPACE 1#body_extension]]
                    ;; MUST NOT be returned on non-extensible
                    ;; "BODY" fetch

body_fields     ::= body_fld_param SPACE body_fld_id SPACE
                    body_fld_desc SPACE body_fld_enc SPACE
                    body_fld_octets

body_fld_desc   ::= nstring

body_fld_dsp    ::= "(" string SPACE body_fld_param ")" / nil

body_fld_enc    ::= (<"> ("7BIT" / "8BIT" / "BINARY" / "BASE64"/
                    "QUOTED-PRINTABLE") <">) / string

body_fld_id     ::= nstring

body_fld_lang   ::= nstring / "(" 1#string ")"

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body_fld_lines  ::= number

body_fld_md5    ::= nstring

body_fld_octets ::= number

body_fld_param  ::= "(" 1#(string SPACE string) ")" / nil

body_type_1part ::= (body_type_basic / body_type_msg / body_type_text)
                    [SPACE body_ext_1part]

body_type_basic ::= media_basic SPACE body_fields
                    ;; MESSAGE subtype MUST NOT be "RFC822"

body_type_mpart ::= 1*body SPACE media_subtype
                    [SPACE body_ext_mpart]

body_type_msg   ::= media_message SPACE body_fields SPACE envelope
                    SPACE body SPACE body_fld_lines

body_type_text  ::= media_text SPACE body_fields SPACE body_fld_lines

capability      ::= "AUTH=" auth_type / atom
                    ;; New capabilities MUST begin with "X" or be
                    ;; registered with IANA as standard or
                    ;; standards-track

capability_data ::= "CAPABILITY" SPACE [1#capability SPACE] "IMAP4rev1"
                    [SPACE 1#capability]
                    ;; IMAP4rev1 servers which offer RFC 1730
                    ;; compatibility MUST list "IMAP4" as the first
                    ;; capability.

CHAR            ::= <any 7-bit US-ASCII character except NUL,
                     0x01 - 0x7f>

CHAR8           ::= <any 8-bit octet except NUL, 0x01 - 0xff>

command         ::= tag SPACE (command_any / command_auth /
                    command_nonauth / command_select) CRLF
                    ;; Modal based on state

command_any     ::= "CAPABILITY" / "LOGOUT" / "NOOP" / x_command
                    ;; Valid in all states

command_auth    ::= append / create / delete / examine / list / lsub /
                    rename / select / status / subscribe / unsubscribe
                    ;; Valid only in Authenticated or Selected state

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command_nonauth ::= login / authenticate
                    ;; Valid only when in Non-Authenticated state

command_select  ::= "CHECK" / "CLOSE" / "EXPUNGE" /
                     copy / fetch / store / uid / search
                    ;; Valid only when in Selected state

continue_req    ::= "+" SPACE (resp_text / base64)

copy            ::= "COPY" SPACE set SPACE mailbox

CR              ::= <ASCII CR, carriage return, 0x0D>

create          ::= "CREATE" SPACE mailbox
                    ;; Use of INBOX gives a NO error

CRLF            ::= CR LF

CTL             ::= <any ASCII control character and DEL,
                        0x00 - 0x1f, 0x7f>

date            ::= date_text / <"> date_text <">

date_day        ::= 1*2digit
                    ;; Day of month

date_day_fixed  ::= (SPACE digit) / 2digit
                    ;; Fixed-format version of date_day

date_month      ::= "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" /
                    "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec"

date_text       ::= date_day "-" date_month "-" date_year

date_year       ::= 4digit

date_time       ::= <"> date_day_fixed "-" date_month "-" date_year
                    SPACE time SPACE zone <">

delete          ::= "DELETE" SPACE mailbox
                    ;; Use of INBOX gives a NO error

digit           ::= "0" / digit_nz

digit_nz        ::= "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" /
                    "9"

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envelope        ::= "(" env_date SPACE env_subject SPACE env_from
                    SPACE env_sender SPACE env_reply_to SPACE env_to
                    SPACE env_cc SPACE env_bcc SPACE env_in_reply_to
                    SPACE env_message_id ")"

env_bcc         ::= "(" 1*address ")" / nil

env_cc          ::= "(" 1*address ")" / nil

env_date        ::= nstring

env_from        ::= "(" 1*address ")" / nil

env_in_reply_to ::= nstring

env_message_id  ::= nstring

env_reply_to    ::= "(" 1*address ")" / nil

env_sender      ::= "(" 1*address ")" / nil

env_subject     ::= nstring

env_to          ::= "(" 1*address ")" / nil

examine         ::= "EXAMINE" SPACE mailbox

fetch           ::= "FETCH" SPACE set SPACE ("ALL" / "FULL" /
                    "FAST" / fetch_att / "(" 1#fetch_att ")")

fetch_att       ::= "ENVELOPE" / "FLAGS" / "INTERNALDATE" /
                    "RFC822" [".HEADER" / ".SIZE" / ".TEXT"] /
                    "BODY" ["STRUCTURE"] / "UID" /
                    "BODY" [".PEEK"] section
                    ["<" number "." nz_number ">"]

flag            ::= "\Answered" / "\Flagged" / "\Deleted" /
                    "\Seen" / "\Draft" / flag_keyword / flag_extension

flag_extension  ::= "\" atom
                    ;; Future expansion.  Client implementations
                    ;; MUST accept flag_extension flags.  Server
                    ;; implementations MUST NOT generate
                    ;; flag_extension flags except as defined by
                    ;; future standard or standards-track
                    ;; revisions of this specification.

flag_keyword    ::= atom

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flag_list       ::= "(" #flag ")"

greeting        ::= "*" SPACE (resp_cond_auth / resp_cond_bye) CRLF

header_fld_name ::= astring

header_list     ::= "(" 1#header_fld_name ")"

LF              ::= <ASCII LF, line feed, 0x0A>

list            ::= "LIST" SPACE mailbox SPACE list_mailbox

list_mailbox    ::= 1*(ATOM_CHAR / list_wildcards) / string

list_wildcards  ::= "%" / "*"

literal         ::= "{" number "}" CRLF *CHAR8
                    ;; Number represents the number of CHAR8 octets

login           ::= "LOGIN" SPACE userid SPACE password

lsub            ::= "LSUB" SPACE mailbox SPACE list_mailbox

mailbox         ::= "INBOX" / astring
                    ;; INBOX is case-insensitive.  All case variants of
                    ;; INBOX (e.g. "iNbOx") MUST be interpreted as INBOX
                    ;; not as an astring.  Refer to section 5.1 for
                    ;; further semantic details of mailbox names.

mailbox_data    ::=  "FLAGS" SPACE flag_list /
                     "LIST" SPACE mailbox_list /
                     "LSUB" SPACE mailbox_list /
                     "MAILBOX" SPACE text /
                     "SEARCH" [SPACE 1#nz_number] /
                     "STATUS" SPACE mailbox SPACE
                     "(" #<status_att number ")" /
                     number SPACE "EXISTS" / number SPACE "RECENT"

mailbox_list    ::= "(" #("\Marked" / "\Noinferiors" /
                    "\Noselect" / "\Unmarked" / flag_extension) ")"
                    SPACE (<"> QUOTED_CHAR <"> / nil) SPACE mailbox

media_basic     ::= (<"> ("APPLICATION" / "AUDIO" / "IMAGE" /
                    "MESSAGE" / "VIDEO") <">) / string)
                    SPACE media_subtype
                    ;; Defined in [MIME-IMT]

media_message   ::= <"> "MESSAGE" <"> SPACE <"> "RFC822" <">

Top      Up      ToC       Page 71 
                    ;; Defined in [MIME-IMT]

media_subtype   ::= string
                    ;; Defined in [MIME-IMT]

media_text      ::= <"> "TEXT" <"> SPACE media_subtype
                    ;; Defined in [MIME-IMT]

message_data    ::= nz_number SPACE ("EXPUNGE" /
                                    ("FETCH" SPACE msg_att))

msg_att         ::= "(" 1#("ENVELOPE" SPACE envelope /
                    "FLAGS" SPACE "(" #(flag / "\Recent") ")" /
                    "INTERNALDATE" SPACE date_time /
                    "RFC822" [".HEADER" / ".TEXT"] SPACE nstring /
                    "RFC822.SIZE" SPACE number /
                    "BODY" ["STRUCTURE"] SPACE body /
                    "BODY" section ["<" number ">"] SPACE nstring /
                    "UID" SPACE uniqueid) ")"

nil             ::= "NIL"

nstring         ::= string / nil

number          ::= 1*digit
                    ;; Unsigned 32-bit integer
                    ;; (0 <= n < 4,294,967,296)

nz_number       ::= digit_nz *digit
                    ;; Non-zero unsigned 32-bit integer
                    ;; (0 < n < 4,294,967,296)

password        ::= astring

quoted          ::= <"> *QUOTED_CHAR <">

QUOTED_CHAR     ::= <any TEXT_CHAR except quoted_specials> /
                    "\" quoted_specials

quoted_specials ::= <"> / "\"

rename          ::= "RENAME" SPACE mailbox SPACE mailbox
                    ;; Use of INBOX as a destination gives a NO error

response        ::= *(continue_req / response_data) response_done

response_data   ::= "*" SPACE (resp_cond_state / resp_cond_bye /
                    mailbox_data / message_data / capability_data)

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                    CRLF

response_done   ::= response_tagged / response_fatal

response_fatal  ::= "*" SPACE resp_cond_bye CRLF
                    ;; Server closes connection immediately

response_tagged ::= tag SPACE resp_cond_state CRLF

resp_cond_auth  ::= ("OK" / "PREAUTH") SPACE resp_text
                    ;; Authentication condition

resp_cond_bye   ::= "BYE" SPACE resp_text

resp_cond_state ::= ("OK" / "NO" / "BAD") SPACE resp_text
                    ;; Status condition

resp_text       ::= ["[" resp_text_code "]" SPACE] (text_mime2 / text)
                    ;; text SHOULD NOT begin with "[" or "="

resp_text_code  ::= "ALERT" / "PARSE" /
                    "PERMANENTFLAGS" SPACE "(" #(flag / "\*") ")" /
                    "READ-ONLY" / "READ-WRITE" / "TRYCREATE" /
                    "UIDVALIDITY" SPACE nz_number /
                    "UNSEEN" SPACE nz_number /
                    atom [SPACE 1*<any TEXT_CHAR except "]">]

search          ::= "SEARCH" SPACE ["CHARSET" SPACE astring SPACE]
                    1#search_key
                    ;; [CHARSET] MUST be registered with IANA

search_key      ::= "ALL" / "ANSWERED" / "BCC" SPACE astring /
                    "BEFORE" SPACE date / "BODY" SPACE astring /
                    "CC" SPACE astring / "DELETED" / "FLAGGED" /
                    "FROM" SPACE astring /
                    "KEYWORD" SPACE flag_keyword / "NEW" / "OLD" /
                    "ON" SPACE date / "RECENT" / "SEEN" /
                    "SINCE" SPACE date / "SUBJECT" SPACE astring /
                    "TEXT" SPACE astring / "TO" SPACE astring /
                    "UNANSWERED" / "UNDELETED" / "UNFLAGGED" /
                    "UNKEYWORD" SPACE flag_keyword / "UNSEEN" /
                    ;; Above this line were in [IMAP2]
                    "DRAFT" /
                    "HEADER" SPACE header_fld_name SPACE astring /
                    "LARGER" SPACE number / "NOT" SPACE search_key /
                    "OR" SPACE search_key SPACE search_key /
                    "SENTBEFORE" SPACE date / "SENTON" SPACE date /
                    "SENTSINCE" SPACE date / "SMALLER" SPACE number /

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                    "UID" SPACE set / "UNDRAFT" / set /
                    "(" 1#search_key ")"

section         ::= "[" [section_text / (nz_number *["." nz_number]
                    ["." (section_text / "MIME")])] "]"

section_text    ::= "HEADER" / "HEADER.FIELDS" [".NOT"]
                    SPACE header_list / "TEXT"

select          ::= "SELECT" SPACE mailbox

sequence_num    ::= nz_number / "*"
                    ;; * is the largest number in use.  For message
                    ;; sequence numbers, it is the number of messages
                    ;; in the mailbox.  For unique identifiers, it is
                    ;; the unique identifier of the last message in
                    ;; the mailbox.

set             ::= sequence_num / (sequence_num ":" sequence_num) /
                    (set "," set)
                    ;; Identifies a set of messages.  For message
                    ;; sequence numbers, these are consecutive
                    ;; numbers from 1 to the number of messages in
                    ;; the mailbox
                    ;; Comma delimits individual numbers, colon
                    ;; delimits between two numbers inclusive.
                    ;; Example: 2,4:7,9,12:* is 2,4,5,6,7,9,12,13,
                    ;; 14,15 for a mailbox with 15 messages.

SPACE           ::= <ASCII SP, space, 0x20>

status          ::= "STATUS" SPACE mailbox SPACE "(" 1#status_att ")"

status_att      ::= "MESSAGES" / "RECENT" / "UIDNEXT" / "UIDVALIDITY" /
                    "UNSEEN"

store           ::= "STORE" SPACE set SPACE store_att_flags

store_att_flags ::= (["+" / "-"] "FLAGS" [".SILENT"]) SPACE
                    (flag_list / #flag)

string          ::= quoted / literal

subscribe       ::= "SUBSCRIBE" SPACE mailbox

tag             ::= 1*<any ATOM_CHAR except "+">

text            ::= 1*TEXT_CHAR

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text_mime2       ::= "=?" <charset> "?" <encoding> "?"
                     <encoded-text> "?="
                     ;; Syntax defined in [MIME-HDRS]

TEXT_CHAR       ::= <any CHAR except CR and LF>

time            ::= 2digit ":" 2digit ":" 2digit
                    ;; Hours minutes seconds

uid             ::= "UID" SPACE (copy / fetch / search / store)
                    ;; Unique identifiers used instead of message
                    ;; sequence numbers

uniqueid        ::= nz_number
                    ;; Strictly ascending

unsubscribe     ::= "UNSUBSCRIBE" SPACE mailbox

userid          ::= astring

x_command       ::= "X" atom <experimental command arguments>

zone            ::= ("+" / "-") 4digit
                    ;; Signed four-digit value of hhmm representing
                    ;; hours and minutes west of Greenwich (that is,
                    ;; (the amount that the given time differs from
                    ;; Universal Time).  Subtracting the timezone
                    ;; from the given time will give the UT form.
                    ;; The Universal Time zone is "+0000".

10.     Author's Note

   This document is a revision or rewrite of earlier documents, and
   supercedes the protocol specification in those documents: RFC 1730,
   unpublished IMAP2bis.TXT document, RFC 1176, and RFC 1064.

11.     Security Considerations

   IMAP4rev1 protocol transactions, including electronic mail data, are
   sent in the clear over the network unless privacy protection is
   negotiated in the AUTHENTICATE command.

   A server error message for an AUTHENTICATE command which fails due to
   invalid credentials SHOULD NOT detail why the credentials are
   invalid.

   Use of the LOGIN command sends passwords in the clear.  This can be
   avoided by using the AUTHENTICATE command instead.

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   A server error message for a failing LOGIN command SHOULD NOT specify
   that the user name, as opposed to the password, is invalid.

   Additional security considerations are discussed in the section
   discussing the AUTHENTICATE and LOGIN commands.

12.     Author's Address

   Mark R. Crispin
   Networks and Distributed Computing
   University of Washington
   4545 15th Aveneue NE
   Seattle, WA  98105-4527

   Phone: (206) 543-5762

   EMail: MRC@CAC.Washington.EDU

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Appendices

A.      References

[ACAP] Myers, J. "ACAP -- Application Configuration Access Protocol",
Work in Progress.

[CHARSET] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2,
RFC 1700, USC/Information Sciences Institute, October 1994.

[DISPOSITION] Troost, R., and Dorner, S., "Communicating Presentation
Information in Internet Messages: The Content-Disposition Header",
RFC 1806, June 1995.

[IMAP-AUTH] Myers, J., "IMAP4 Authentication Mechanism", RFC 1731.
Carnegie-Mellon University, December 1994.

[IMAP-COMPAT] Crispin, M., "IMAP4 Compatibility with IMAP2bis", RFC
2061, University of Washington, November 1996.

[IMAP-DISC] Austein, R., "Synchronization Operations for Disconnected
IMAP4 Clients", Work in Progress.

[IMAP-HISTORICAL] Crispin, M. "IMAP4 Compatibility with IMAP2 and
IMAP2bis", RFC 1732, University of Washington, December 1994.

[IMAP-MODEL] Crispin, M., "Distributed Electronic Mail Models in
IMAP4", RFC 1733, University of Washington, December 1994.

[IMAP-OBSOLETE] Crispin, M., "Internet Message Access Protocol -
Obsolete Syntax", RFC 2062, University of Washington, November 1996.

[IMAP2] Crispin, M., "Interactive Mail Access Protocol - Version 2",
RFC 1176, University of Washington, August 1990.

[LANGUAGE-TAGS] Alvestrand, H., "Tags for the Identification of
Languages", RFC 1766, March 1995.

[MD5] Myers, J., and M. Rose, "The Content-MD5 Header Field", RFC
1864, October 1995.

[MIME-IMB] Freed, N., and N. Borenstein, "MIME (Multipurpose Internet
Mail Extensions) Part One: Format of Internet Message Bodies", RFC
2045, November 1996.

[MIME-IMT] Freed, N., and N. Borenstein, "MIME (Multipurpose
Internet Mail Extensions) Part Two: Media Types", RFC 2046,
November 1996.

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[MIME-HDRS] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
Part Three: Message Header Extensions for Non-ASCII Text", RFC
2047, November 1996.

[RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", STD 11, RFC 822, University of Delaware, August 1982.

[SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10,
RFC 821, USC/Information Sciences Institute, August 1982.

[UTF-7] Goldsmith, D., and Davis, M., "UTF-7: A Mail-Safe
Transformation Format of Unicode", RFC 1642, July 1994.

B.      Changes from RFC 1730

1) The STATUS command has been added.

2) Clarify in the formal syntax that the "#" construct can never
refer to multiple spaces.

3) Obsolete syntax has been moved to a separate document.

4) The PARTIAL command has been obsoleted.

5) The RFC822.HEADER.LINES, RFC822.HEADER.LINES.NOT, RFC822.PEEK, and
RFC822.TEXT.PEEK fetch attributes have been obsoleted.

6) The "<" origin "." size ">" suffix for BODY text attributes has
been added.

7) The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, and TEXT part
specifiers have been added.

8) Support for Content-Disposition and Content-Language has been
added.

9) The restriction on fetching nested MULTIPART parts has been
removed.

10) Body part number 0 has been obsoleted.

11) Server-supported authenticators are now identified by
capabilities.

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12) The capability that identifies this protocol is now called
"IMAP4rev1".  A server that provides backwards support for RFC 1730
SHOULD emit the "IMAP4" capability in addition to "IMAP4rev1" in its
CAPABILITY response.  Because RFC-1730 required "IMAP4" to appear as
the first capability, it MUST listed first in the response.

13) A description of the mailbox name namespace convention has been
added.

14) A description of the international mailbox name convention has
been added.

15) The UID-NEXT and UID-VALIDITY status items are now called UIDNEXT
and UIDVALIDITY.  This is a change from the IMAP STATUS
Work in Progress and not from RFC-1730

16) Add a clarification that a null mailbox name argument to the LIST
command returns an untagged LIST response with the hierarchy
delimiter and root of the reference argument.

17) Define terms such as "MUST", "SHOULD", and "MUST NOT".

18) Add a section which defines message attributes and more
thoroughly details the semantics of message sequence numbers, UIDs,
and flags.

19) Add a clarification detailing the circumstances when a client may
send multiple commands without waiting for a response, and the
circumstances in which ambiguities may result.

20) Add a recommendation on server behavior for DELETE and RENAME
when inferior hierarchical names of the given name exist.

21) Add a clarification that a mailbox name may not be unilaterally
unsubscribed by the server, even if that mailbox name no longer
exists.

22) Add a clarification that LIST should return its results quickly
without undue delay.

23) Add a clarification that the date_time argument to APPEND sets
the internal date of the message.

24) Add a clarification on APPEND behavior when the target mailbox is
the currently selected mailbox.

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25) Add a clarification that external changes to flags should be
always announced via an untagged FETCH even if the current command is
a STORE with the ".SILENT" suffix.

26) Add a clarification that COPY appends to the target mailbox.

27) Add the NEWNAME response code.

28) Rewrite the description of the untagged BYE response to clarify
its semantics.

29) Change the reference for the body MD5 to refer to the proper RFC.

30) Clarify that the formal syntax contains rules which may overlap,
and that in the event of such an overlap the rule which occurs first
takes precedence.

31) Correct the definition of body_fld_param.

32) More formal syntax for capability_data.

33) Clarify that any case variant of "INBOX" must be interpreted as
INBOX.

34) Clarify that the human-readable text in resp_text should not
begin with "[" or "=".

35) Change MIME references to Draft Standard documents.

36) Clarify \Recent semantics.

37) Additional examples.

C.      Key Word Index

       +FLAGS <flag list> (store command data item) ...............   45
       +FLAGS.SILENT <flag list> (store command data item) ........   46
       -FLAGS <flag list> (store command data item) ...............   46
       -FLAGS.SILENT <flag list> (store command data item) ........   46
       ALERT (response code) ......................................   50
       ALL (fetch item) ...........................................   41
       ALL (search key) ...........................................   38
       ANSWERED (search key) ......................................   38
       APPEND (command) ...........................................   34
       AUTHENTICATE (command) .....................................   20
       BAD (response) .............................................   52
       BCC <string> (search key) ..................................   38
       BEFORE <date> (search key) .................................   39

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       BODY (fetch item) ..........................................   41
       BODY (fetch result) ........................................   58
       BODY <string> (search key) .................................   39
       BODY.PEEK[<section>]<<partial>> (fetch item) ...............   44
       BODYSTRUCTURE (fetch item) .................................   44
       BODYSTRUCTURE (fetch result) ...............................   59
       BODY[<section>]<<origin_octet>> (fetch result) .............   58
       BODY[<section>]<<partial>> (fetch item) ....................   41
       BYE (response) .............................................   52
       Body Structure (message attribute) .........................   11
       CAPABILITY (command) .......................................   18
       CAPABILITY (response) ......................................   53
       CC <string> (search key) ...................................   39
       CHECK (command) ............................................   36
       CLOSE (command) ............................................   36
       COPY (command) .............................................   46
       CREATE (command) ...........................................   25
       DELETE (command) ...........................................   26
       DELETED (search key) .......................................   39
       DRAFT (search key) .........................................   39
       ENVELOPE (fetch item) ......................................   44
       ENVELOPE (fetch result) ....................................   62
       EXAMINE (command) ..........................................   24
       EXISTS (response) ..........................................   56
       EXPUNGE (command) ..........................................   37
       EXPUNGE (response) .........................................   57
       Envelope Structure (message attribute) .....................   11
       FAST (fetch item) ..........................................   44
       FETCH (command) ............................................   41
       FETCH (response) ...........................................   58
       FLAGGED (search key) .......................................   39
       FLAGS (fetch item) .........................................   44
       FLAGS (fetch result) .......................................   62
       FLAGS (response) ...........................................   56
       FLAGS <flag list> (store command data item) ................   45
       FLAGS.SILENT <flag list> (store command data item) .........   45
       FROM <string> (search key) .................................   39
       FULL (fetch item) ..........................................   44
       Flags (message attribute) ..................................    9
       HEADER (part specifier) ....................................   41
       HEADER <field-name> <string> (search key) ..................   39
       HEADER.FIELDS <header_list> (part specifier) ...............   41
       HEADER.FIELDS.NOT <header_list> (part specifier) ...........   41
       INTERNALDATE (fetch item) ..................................   44
       INTERNALDATE (fetch result) ................................   62
       Internal Date (message attribute) ..........................   10
       KEYWORD <flag> (search key) ................................   39
       Keyword (type of flag) .....................................   10

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       LARGER <n> (search key) ....................................   39
       LIST (command) .............................................   30
       LIST (response) ............................................   54
       LOGIN (command) ............................................   22
       LOGOUT (command) ...........................................   20
       LSUB (command) .............................................   32
       LSUB (response) ............................................   55
       MAY (specification requirement term) .......................    5
       MESSAGES (status item) .....................................   33
       MIME (part specifier) ......................................   42
       MUST (specification requirement term) ......................    4
       MUST NOT (specification requirement term) ..................    4
       Message Sequence Number (message attribute) ................    9
       NEW (search key) ...........................................   39
       NEWNAME (response code) ....................................   50
       NO (response) ..............................................   51
       NOOP (command) .............................................   19
       NOT <search-key> (search key) ..............................   39
       OK (response) ..............................................   51
       OLD (search key) ...........................................   39
       ON <date> (search key) .....................................   39
       OPTIONAL (specification requirement term) ..................    5
       OR <search-key1> <search-key2> (search key) ................   39
       PARSE (response code) ......................................   50
       PERMANENTFLAGS (response code) .............................   50
       PREAUTH (response) .........................................   52
       Permanent Flag (class of flag) .............................   10
       READ-ONLY (response code) ..................................   50
       READ-WRITE (response code) .................................   50
       RECENT (response) ..........................................   57
       RECENT (search key) ........................................   39
       RECENT (status item) .......................................   33
       RENAME (command) ...........................................   27
       REQUIRED (specification requirement term) ..................    4
       RFC822 (fetch item) ........................................   44
       RFC822 (fetch result) ......................................   63
       RFC822.HEADER (fetch item) .................................   44
       RFC822.HEADER (fetch result) ...............................   62
       RFC822.SIZE (fetch item) ...................................   44
       RFC822.SIZE (fetch result) .................................   62
       RFC822.TEXT (fetch item) ...................................   44
       RFC822.TEXT (fetch result) .................................   62
       SEARCH (command) ...........................................   37
       SEARCH (response) ..........................................   55
       SEEN (search key) ..........................................   40
       SELECT (command) ...........................................   23
       SENTBEFORE <date> (search key) .............................   40
       SENTON <date> (search key) .................................   40

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       SENTSINCE <date> (search key) ..............................   40
       SHOULD (specification requirement term) ....................    5
       SHOULD NOT (specification requirement term) ................    5
       SINCE <date> (search key) ..................................   40
       SMALLER <n> (search key) ...................................   40
       STATUS (command) ...........................................   33
       STATUS (response) ..........................................   55
       STORE (command) ............................................   45
       SUBJECT <string> (search key) ..............................   40
       SUBSCRIBE (command) ........................................   29
       Session Flag (class of flag) ...............................   10
       System Flag (type of flag) .................................    9
       TEXT (part specifier) ......................................   42
       TEXT <string> (search key) .................................   40
       TO <string> (search key) ...................................   40
       TRYCREATE (response code) ..................................   51
       UID (command) ..............................................   47
       UID (fetch item) ...........................................   44
       UID (fetch result) .........................................   63
       UID <message set> (search key) .............................   40
       UIDNEXT (status item) ......................................   33
       UIDVALIDITY (response code) ................................   51
       UIDVALIDITY (status item) ..................................   34
       UNANSWERED (search key) ....................................   40
       UNDELETED (search key) .....................................   40
       UNDRAFT (search key) .......................................   40
       UNFLAGGED (search key) .....................................   40
       UNKEYWORD <flag> (search key) ..............................   40
       UNSEEN (response code) .....................................   51
       UNSEEN (search key) ........................................   40
       UNSEEN (status item) .......................................   34
       UNSUBSCRIBE (command) ......................................   30
       Unique Identifier (UID) (message attribute) ................    7
       X<atom> (command) ..........................................   48
       [RFC-822] Size (message attribute) .........................   11
       \Answered (system flag) ....................................    9
       \Deleted (system flag) .....................................    9
       \Draft (system flag) .......................................    9
       \Flagged (system flag) .....................................    9
       \Marked (mailbox name attribute) ...........................   54
       \Noinferiors (mailbox name attribute) ......................   54
       \Noselect (mailbox name attribute) .........................   54
       \Recent (system flag) ......................................   10
       \Seen (system flag) ........................................    9
       \Unmarked (mailbox name attribute) .........................   54