[Dovecot] aha! (was apple mail vs. v0.99)

[Dominik 'Rathann' Mierzejewski]

Hello,

On Mon, Mar 14, 2005 at 12:03:24PM -0500, sean finney wrote:
> it seems that when you say "check for new mail" in apple mail, it sends
> a NOOP to the imap server to get the response.   in uw, the conversation
> is something like:
> 
> 25 NOOP
> 25 OK NOOP completed
> 26 NOOP
> * 2796 EXISTS
> * 7 RECENT
> 26 OK NOOP completed
> 
> however, with dovecot, if it has already notified the client that new
> mail has arrived, it will look something like:
> 
> * 24 EXISTS
> * 2 RECENT
> 22 NOOP
> 22 OK NOOP completed.
> 23 NOOP
> 23 OK NOOP completed.
> 
> (the counts are different because these are seperate accounts)
> 
> so evidently, apple mail is too stupid to realize to read info from the
> server unless it asked for it...
> 
> so now that i think i have a short-term fix (disabling notification for 
> new mail server-side), i can breathe a sigh of relief.  for a long-term
> fix, would it be possible to have the server always notify the client
> of new mail after a NOOP?

According to RFC3501 (is this the right one?), NOOP can be used to check
for new mail, but it doesn't say that the server should return status
data every time NOOP is issued.

[...]
      The NOOP command always succeeds.  It does nothing.

      Since any command can return a status update as untagged data, the
      NOOP command can be used as a periodic poll for new messages or
      message status updates during a period of inactivity (this is the
      preferred method to do this).  The NOOP command can also be used
      to reset any inactivity autologout timer on the server.
[...]

The RFC states that the IMAP server MUST send status data to the client
if and when mailbox size changes (and I assume dovecot does that) but
again, once is assumed enough and the client is REQUIRED to record any status
updates (5.2):
[...]
   Regardless of what implementation decisions a client makes on
   remembering data from the server, a client implementation MUST record
   mailbox size updates.  It MUST NOT assume that any command after the
   initial mailbox selection will return the size of the mailbox.
[...]

Clearly, Apple Mail breaks the RFC if it assumes that the server will
report the same data over and over again after each NOOP.
There is a standard way to poll for new messages, i.e. using RECENT
and EXISTS commands (7.3.1 and 7.3.2). If Apple Mail did that instead of
using NOOP, there'd be no problem.

Please, don't hesitate to correct me if I'm wrong.

Regards,

-- 
Dominik 'Rathann' Mierzejewski <rathann*at*icm.edu.pl>
Interdisciplinary Centre for Mathematical and Computational Modelling
Warsaw University  |  http://www.icm.edu.pl  |  tel. +48 (22) 5540810