I've upgrade my 5.0.0 to 5.0.1 yesterday and everything was ok during the process. When i started my zimbra anti virus service seems to be started but in the logs i can see that mails can not be delivered to the mail boxes. I saw that actione before on other releases but it was causing a %99 cpu activity and after 5-6 minutes, things become normal and mails got delivered. With the new version i waited for more than 3 hours to settle things down but nothing has changed.
I stopped the antivirus service and new mails arrived afterwards. Also i did a requeue and old mails also came in to mailboxes. Now my system works without antivirus (i have a bridge firewall before the system which takes care of the problem) and things are ok.
Centos 4.5 / Zimbra 5.0.1GA RHE4x86