rfc2060_imap.txt

邮件编码格式说明。

   In authenticated state, commands that manipulate mailboxes as atomic
   entities are permitted.  Of these commands, the SELECT and EXAMINE
   commands will select a mailbox for access and enter selected state.

   In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT),
   the following commands are valid in authenticated state: SELECT,
   EXAMINE, CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, LSUB,
   STATUS, and APPEND.





Crispin                     Standards Track                    [Page 22]

RFC 2060                       IMAP4rev1                   December 1996


6.3.1.  SELECT Command

   Arguments:  mailbox name

   Responses:  REQUIRED untagged responses: FLAGS, EXISTS, RECENT
               OPTIONAL OK untagged responses: UNSEEN, PERMANENTFLAGS

   Result:     OK - select completed, now in selected state
               NO - select failure, now in authenticated state: no
                    such mailbox, can't access mailbox
               BAD - command unknown or arguments invalid

   The SELECT command selects a mailbox so that messages in the
   mailbox can be accessed.  Before returning an OK to the client,
   the server MUST send the following untagged data to the client:

      FLAGS       Defined flags in the mailbox.  See the description
                  of the FLAGS response for more detail.

      <n> EXISTS  The number of messages in the mailbox.  See the
                  description of the EXISTS response for more detail.

      <n> RECENT  The number of messages with the \Recent flag set.
                  See the description of the RECENT response for more
                  detail.

      OK [UIDVALIDITY <n>]
                  The unique identifier validity value.  See the
                  description of the UID command for more detail.

   to define the initial state of the mailbox at the client.

   The server SHOULD also send an UNSEEN response code in an OK
   untagged response, indicating the message sequence number of the
   first unseen message in the mailbox.

   If the client can not change the permanent state of one or more of
   the flags listed in the FLAGS untagged response, the server SHOULD
   send a PERMANENTFLAGS response code in an OK untagged response,
   listing the flags that the client can change permanently.

   Only one mailbox can be selected at a time in a connection;
   simultaneous access to multiple mailboxes requires multiple
   connections.  The SELECT command automatically deselects any
   currently selected mailbox before attempting the new selection.
   Consequently, if a mailbox is selected and a SELECT command that
   fails is attempted, no mailbox is selected.




Crispin                     Standards Track                    [Page 23]

RFC 2060                       IMAP4rev1                   December 1996


   If the client is permitted to modify the mailbox, the server
   SHOULD prefix the text of the tagged OK response with the
         "[READ-WRITE]" response code.

      If the client is not permitted to modify the mailbox but is
      permitted read access, the mailbox is selected as read-only, and
      the server MUST prefix the text of the tagged OK response to
      SELECT with the "[READ-ONLY]" response code.  Read-only access
      through SELECT differs from the EXAMINE command in that certain
      read-only mailboxes MAY permit the change of permanent state on a
      per-user (as opposed to global) basis.  Netnews messages marked in
      a server-based .newsrc file are an example of such per-user
      permanent state that can be modified with read-only mailboxes.

   Example:    C: A142 SELECT INBOX
               S: * 172 EXISTS
               S: * 1 RECENT
               S: * OK [UNSEEN 12] Message 12 is first unseen
               S: * OK [UIDVALIDITY 3857529045] UIDs valid
               S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
               S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited
               S: A142 OK [READ-WRITE] SELECT completed

6.3.2.  EXAMINE Command

   Arguments:  mailbox name

   Responses:  REQUIRED untagged responses: FLAGS, EXISTS, RECENT
               OPTIONAL OK untagged responses: UNSEEN, PERMANENTFLAGS

   Result:     OK - examine completed, now in selected state
               NO - examine failure, now in authenticated state: no
                    such mailbox, can't access mailbox
               BAD - command unknown or arguments invalid

      The EXAMINE command is identical to SELECT and returns the same
      output; however, the selected mailbox is identified as read-only.
      No changes to the permanent state of the mailbox, including
      per-user state, are permitted.












Crispin                     Standards Track                    [Page 24]

RFC 2060                       IMAP4rev1                   December 1996


      The text of the tagged OK response to the EXAMINE command MUST
      begin with the "[READ-ONLY]" response code.

   Example:    C: A932 EXAMINE blurdybloop
               S: * 17 EXISTS
               S: * 2 RECENT
               S: * OK [UNSEEN 8] Message 8 is first unseen
               S: * OK [UIDVALIDITY 3857529045] UIDs valid
               S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
               S: * OK [PERMANENTFLAGS ()] No permanent flags permitted
               S: A932 OK [READ-ONLY] EXAMINE completed

6.3.3.  CREATE Command

   Arguments:  mailbox name

   Responses:  no specific responses for this command

   Result:     OK - create completed
               NO - create failure: can't create mailbox with that name
               BAD - command unknown or arguments invalid

      The CREATE command creates a mailbox with the given name.  An OK
      response is returned only if a new mailbox with that name has been
      created.  It is an error to attempt to create INBOX or a mailbox
      with a name that refers to an extant mailbox.  Any error in
      creation will return a tagged NO response.

      If the mailbox name is suffixed with the server's hierarchy
      separator character (as returned from the server by a LIST
      command), this is a declaration that the client intends to create
      mailbox names under this name in the hierarchy.  Server
      implementations that do not require this declaration MUST ignore
      it.

      If the server's hierarchy separator character appears elsewhere in
      the name, the server SHOULD create any superior hierarchical names
      that are needed for the CREATE command to complete successfully.
      In other words, an attempt to create "foo/bar/zap" on a server in
      which "/" is the hierarchy separator character SHOULD create foo/
      and foo/bar/ if they do not already exist.

      If a new mailbox is created with the same name as a mailbox which
      was deleted, its unique identifiers MUST be greater than any
      unique identifiers used in the previous incarnation of the mailbox
      UNLESS the new incarnation has a different unique identifier
      validity value.  See the description of the UID command for more
      detail.



Crispin                     Standards Track                    [Page 25]

RFC 2060                       IMAP4rev1                   December 1996


   Example:    C: A003 CREATE owatagusiam/
               S: A003 OK CREATE completed
               C: A004 CREATE owatagusiam/blurdybloop
               S: A004 OK CREATE completed

      Note: the interpretation of this example depends on whether "/"
      was returned as the hierarchy separator from LIST.  If "/" is the
      hierarchy separator, a new level of hierarchy named "owatagusiam"
      with a member called "blurdybloop" is created.  Otherwise, two
      mailboxes at the same hierarchy level are created.

6.3.4.  DELETE Command

   Arguments:  mailbox name

   Responses:  no specific responses for this command

   Result:     OK - delete completed
               NO - delete failure: can't delete mailbox with that name
               BAD - command unknown or arguments invalid

      The DELETE command permanently removes the mailbox with the given
      name.  A tagged OK response is returned only if the mailbox has
      been deleted.  It is an error to attempt to delete INBOX or a
      mailbox name that does not exist.

      The DELETE command MUST NOT remove inferior hierarchical names.
      For example, if a mailbox "foo" has an inferior "foo.bar"
      (assuming "." is the hierarchy delimiter character), removing
      "foo" MUST NOT remove "foo.bar".  It is an error to attempt to
      delete a name that has inferior hierarchical names and also has
      the \Noselect mailbox name attribute (see the description of the
      LIST response for more details).

      It is permitted to delete a name that has inferior hierarchical
      names and does not have the \Noselect mailbox name attribute.  In
      this case, all messages in that mailbox are removed, and the name
      will acquire the \Noselect mailbox name attribute.

      The value of the highest-used unique identifier of the deleted
      mailbox MUST be preserved so that a new mailbox created with the
      same name will not reuse the identifiers of the former
      incarnation, UNLESS the new incarnation has a different unique
      identifier validity value.  See the description of the UID command
      for more detail.






Crispin                     Standards Track                    [Page 26]

RFC 2060                       IMAP4rev1                   December 1996


   Examples:   C: A682 LIST "" *
               S: * LIST () "/" blurdybloop
               S: * LIST (\Noselect) "/" foo
               S: * LIST () "/" foo/bar
               S: A682 OK LIST completed
               C: A683 DELETE blurdybloop
               S: A683 OK DELETE completed
               C: A684 DELETE foo
               S: A684 NO Name "foo" has inferior hierarchical names
               C: A685 DELETE foo/bar
               S: A685 OK DELETE Completed
               C: A686 LIST "" *
               S: * LIST (\Noselect) "/" foo
               S: A686 OK LIST completed
               C: A687 DELETE foo
               S: A687 OK DELETE Completed


               C: A82 LIST "" *
               S: * LIST () "." blurdybloop
               S: * LIST () "." foo
               S: * LIST () "." foo.bar
               S: A82 OK LIST completed
               C: A83 DELETE blurdybloop
               S: A83 OK DELETE completed
               C: A84 DELETE foo
               S: A84 OK DELETE Completed
               C: A85 LIST "" *
               S: * LIST () "." foo.bar
               S: A85 OK LIST completed
               C: A86 LIST "" %
               S: * LIST (\Noselect) "." foo
               S: A86 OK LIST completed

6.3.5.  RENAME Command

   Arguments:  existing mailbox name
               new mailbox name

   Responses:  no specific responses for this command

   Result:     OK - rename completed
               NO - rename failure: can't rename mailbox with that name,
                    can't rename to mailbox with that name
               BAD - command unknown or arguments invalid

      The RENAME command changes the name of a mailbox.  A tagged OK
      response is returned only if the mailbox has been renamed.  It is



Crispin                     Standards Track                    [Page 27]

RFC 2060                       IMAP4rev1                   December 1996


      an error to attempt to rename from a mailbox name that does not
      exist or to a mailbox name that already exists.  Any error in
      renaming will return a tagged NO response.

      If the name has inferior hierarchical names, then the inferior
      hierarchical names MUST also be renamed.  For example, a rename of
      "foo" to "zap