The following message posted to the Email Administration in Higher Education mailing list may also be of interest to readers of this mailing list ...
---------- Forwarded message ---------- From: [EMAIL PROTECTED] To: Email Administration in Higher Education <[EMAIL PROTECTED]> Date: Wed, 10 Sep 2008 16:26:58 -0400 (EDT) Subject: Re: Blackberry, in all of its awful glory > In the last 24 hours we have had 3 Blackberry IMAP users report problems > reducing their disk space to get under the hard quota we enforce. We see the same problem ... Here at the University of Toronto we have about 12-15 calls per day of customers who are over-quota, for whom "delete" followed by "expunge" doesn't free up storage. Based on a preliminary investigation it appears that the customers suffering this problem all use the Blackberry BIS service. The BIS service appears to have a long running (ie lasts weeks) IMAP session to access the INBOX with an IMAP IDLE. (An IMAP IDLE allows BIS to be notified of new messages essentially right away, without the need for polling.) Our IMAP server supports concurrent IMAP sessions (including concurrent list, fetch, and delete). Our server also appears to support concurrent expunge (ie any client session can do an expunge, and all concurrent IMAP sessions to the same INBOX all see the INBOX has been expunged), but actual freeing of space (sometimes called "burping"), only happens when a session is able to get exclusive access to the INBOX. As far as we can see, RIM's BIS server is acting according to IMAP standards. The problem lies in the inability to perform burping with concurrent access. As a bypass to the this problem, we are currently considering killing BIS initiated TCP/IP sessions every 10 minutes, if the customer is over-quota. Technical details We think the problem has been happening since about mid-August. We don't know if something changed around then (e.g. did RIM start supporting IMAP IDLE around that time?) Looking at IMAP logs, one sees many short lived connections from the RIM BIS service. (We haven't confirmed this, but these are likely to be for fetching messages.) One needs to do a "ps" to see the long living IMAP processes. Most of the long running BIS initiated IMAP sessions appear to have started on a Saturday. ie right now we see sessions that started Aug 16, Aug 23, and Aug 30. Perhaps RIM restarts BIS servers on Saturdays, rotating which BIS sever is restarted each Saturday ? We use Washington IMAP with MIX format. Mark Crispin documented burping in http://www.washington.edu/imap/documentation/mixfmt.txt.html including "Shared burping has been a problem for every other IMAP server. Most get it wrong, and cause terrible confusion to clients (including client crashes)." References for related problems which may shed light on the current problem, IMAP IDLE KB13816 July 25, 2007 http://www.blackberry.com/btsc/articles/436/KB13816_f.SAL_Public.html Email message delivery from IMAP IDLE integrated accounts is delayed KB13846 Dec 13, 2007 http://www.blackberry.com/btsc/search.do?cmd=displayKC&docType=kc&externalId=KB13846&sliceId=SAL_Public&dialogID=179992621&stateId=1%200%20179994453 Blackberry blocks emails from PC Sep 3, 2008 http://supportforums.blackberry.com/rim/board/message?board.id=8100&thread.id=4468 Alex Nishri University of Toronto _______________________________________________ Imap-uw mailing list [email protected] http://mailman2.u.washington.edu/mailman/listinfo/imap-uw
