[Risotto]

I have the exact same problem here on a RHEL4 server with a networked edition. But we never had a disk fillup or not enough memory. This happened to us today while it happened back in late September too. It never occurred with versions lower than 4.0.1. This is getting annoying because even though we monitor the server's services we are not being notified when the queue begins to grow because of deferred messages. By the way, we got the same error message: read timeout on the local public ip address.

EDIT: To solve the problem we are doing a restart of the services: zmcontrol stop, zmcontrol start. Then, after a few minutes it is possible to flush the queue with postqueue -f. Strangely this is not possible right after the restart. We had to wait a few minutes for the mailserver not to deferr all messages again. It would be great if someone at zimbra could clarify what's happening. We really don't know what was wrong, whether amavis was not accepting connections anymore or mysql was down. These, by the way would be my two guesses, but I wasn't able to confirm this.