RFC 2177 (rfc2177) - Page 2 of 4

IMAP4 IDLE command

RFC 2177                   IMAP4 IDLE command                  June 1997



   Result:     OK - IDLE completed after client sent "DONE"
               NO - failure: the server will not allow the IDLE
                    command at this time
              BAD - command unknown or arguments invalid

   The IDLE command may be used with any IMAP4 server implementation
   that returns "IDLE" as one of the supported capabilities to the
   CAPABILITY command.  If the server does not advertise the IDLE
   capability, the client MUST NOT use the IDLE command and must poll
   for mailbox updates.  In particular, the client MUST continue to be
   able to accept unsolicited untagged responses to ANY command, as
   specified in the base IMAP specification.

   The IDLE command is sent from the client to the server when the
   client is ready to accept unsolicited mailbox update messages.  The
   server requests a response to the IDLE command using the continuation
   ("+") response.  The IDLE command remains active until the client
   responds to the continuation, and as long as an IDLE command is
   active, the server is now free to send untagged EXISTS, EXPUNGE, and
   other messages at any time.

   The IDLE command is terminated by the receipt of a "DONE"
   continuation from the client; such response satisfies the server's
   continuation request.  At that point, the server MAY send any
   remaining queued untagged responses and then MUST immediately send
   the tagged response to the IDLE command and prepare to process other
   commands. As in the base specification, the processing of any new
   command may cause the sending of unsolicited untagged responses,
   subject to the ambiguity limitations.  The client MUST NOT send a
   command while the server is waiting for the DONE, since the server
   will not be able to distinguish a command from a continuation.

   The server MAY consider a client inactive if it has an IDLE command
   running, and if such a server has an inactivity timeout it MAY log
   the client off implicitly at the end of its timeout period.  Because
   of that, clients using IDLE are advised to terminate the IDLE and
   re-issue it at least every 29 minutes to avoid being logged off.
   This still allows a client to receive immediate mailbox updates even
   though it need only "poll" at half hour intervals.











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