I just migrated from a FreeBSD/Sendmail/UW-IMAP setup to RHEL 3/Postfix/Dovecot (1.0a5 currently). Both systems used Procmail as the final delivery agent (into inboxes or .

Since the changeover, things have *mostly* been going ok, but I've been having some problems that I think are locking-related.

I'm getting reports from users about IMAP hangs (mostly from Thunderbird). Sometimes I see this in the Dovecot logs:

ovecot: Feb 06 11:30:45 Error: imap(dbongert): fcntl() failed with mbox file /home/d/dbongert/mail/worklists/tech-partners: Resource temporarily unavailable

Now, I have read that one should have everything that touches a mailbox use the same sort of locking, but that's the thing--these mailboxes are only accessed via dovecot. I'm sure a few users use procmail to filter their mail, but they're in the strict minority here.

As as experiment, I changed these lines to flock rather than fcntl:

mbox_read_locks = flock mbox_write_locks = dotlock flock

But all that seems to have done is removed the fcntl errors from the log file.

These errors seem to be Thunderbird only (1.07-1.5, Linux and Windows clients), but I'm not sure what that means. I've enabled the only thunderbird-specific IMAP workaround I know of: tb-extra-mailbox-sep, but I doubt that has anything to do with this problem.

-- Dan Bongert dbongert@ssc.wisc.edu SSCC Unix System Administrator