I use the "Simple Shell Script" backup method, which among other things stops Zimbra services at night while doing a rsync of the files, then restarts them. We've had to mess with the syntax a few times since I first wrote the script due to some changes in Zimbra code; at present my stop and start commands in the script are:
su - zimbra -c "/opt/zimbra/bin/zmcontrol stop"
su - zimbra -c "/opt/zimbra/bin/zmcontrol start"
Since I have upgraded to 5.0.18 almost two weeks ago I have had it stop and restart successfully most days, but three times (last night being the third), antivirus services failed to start, resulting in a frozen mail queue. All three times, a manual stop and restart (plain-vanilla zmcontrol stop and zmcontrol start as Zimbra user) has brought everything back up with no errors, and the deferred mail scans and comes through.

Thinking the scripting might be the problem, I just tried running a stop and start from script (as root, not as Zimbra user) and everything restarted just fine this way too. I guess that shouldn't be a surprise since 10 times out of 13 it was fine overnight too.

I'm at a loss to know where to look for problems on this. /var/log/zimbra.log shows that antivirus never successfully started after last night's restart, but I can't actually find a reason. I hesitate to post the whole log, as it has ip addresses and email addresses I'd rather not have out in the public. However, if anyone can tell me specific entries I should look for/post, I can obfuscate them and put them up. Other debugging methods welcome too.

Thanks in advance. . .