The issues that Mabry identifies here is definitely a problem, but the normal log message for this condition is "Killed (lost mailbox lock)" and not "Connection Reset".
"Connection Reset", particularly with Outlook, is more commonly associated with Outlook's timeout set very small. Outlook treats IMAP as if it was HTTP and times out very aggressively; this worsens any situation with heavy load and/or large mailbox. The fix for Outlook is to look in the advanced options and set the timeout to the maximum (usually, this is a slider that should be moved all the way to the right). Changing the mailbox format from something other than traditional UNIX format (mbox format) is also a very good idea. I will deal with this in more detail in my next reply. On Tue, 16 Mar 2010, Mabry Tyson wrote:
Mark may correct me, but here's how I understand what we've experienced. It may bear some resemblance to your situation. You will also see the Connection Reset messages if your users are using multiple mail clients (for instance, iPhone, home machine, work machine) simultaneously and they have mbox formatted mailboxes. Especially if their inboxes are large, users will notice delays. In such a case, the imap server is trying to rewrite the inbox (in response to, say, reads of new messages). It has a lock for the duration of the writing (so the larger the file, the longer the time to rewrite). Other mail clients for the same user will eventually lose their lock and then opportunistically grab the lock later, which means the mail client currently in use by the user will have to wait for the lock (resulting in reports of slow access). The high I/O wait time is consistent with writing large mbox files repeatedly. If that's your situation, changing the mailbox format is the easiest way to improve the situation. We moved users to mbx format. It also helps to educate your users to avoid multiple simultaneous clients and to keep the size of their mailboxes down. It helps to have the mail files on the IMAP server (rather than mounted remotely, which only makes the I/O wait time worse).
-- Mark -- http://panda.com/mrc Democracy is two wolves and a sheep deciding what to eat for lunch. Liberty is a well-armed sheep contesting the vote. _______________________________________________ Imap-uw mailing list [email protected] http://mailman2.u.washington.edu/mailman/listinfo/imap-uw
