This situation may be related to this old thread (which doesn't really show a solution), but since I saw it today with 4.5.9 I wanted to post this for comments and info.
This morning I had my entire MTA queue suspend everything that was supposed to be delivered. Each message had a status in the mail queue of "Delivery temporarily suspended", and here's a sample entry from /var/log/mail.log:
zmcontrol stop and start did not accomplish anything, and neither did zmfixperms. However, the thread above suggested "something to do with amavisd", so I tried disabling, and immediately re-enabling, the "Enable spam checking and antivirus" checkbox from the AS/AV tab, global settings, in the UI. Within a minute of doing this all the deferred mail went through.Code:Nov 21 10:58:14 mail postfix/qmgr: 4DA9B3D0C57: to=<firstname.lastname@example.org> , relay=none, delay=3645, status=deferred (delivery temporarily suspended: connect to 127.0.0.1[127.0.0.1]: Connection refused)
I don't have any idea what caused this to hang; however, earlier this morning I changed my spam settings to a lower tag percent (using the UI), and did NOT stop/restart spam filtering. It appears that the queue hung when I did this.
There may be a bug to report in this; I'll wait for further confirmation from other users first. But in the meantime, if you find your formerly-working MTA suspended, try stopping and restarting antispam/antivirus from the UI and see if it kicks it loose for you.
Happy Thanksgiving everyone!
Note: Please see this wiki for complete instructions and descriptions of this issue. The problem may also manifest itself with the warning:
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Local version: X.XX Recommended version: Y.YY
DON'T PANIC! Read `http://www.clamav.net/support/faq`