I'm doing a reinstall of zimbra (5.0.2 GA) on Ubuntu 6.06 and have everything up and running but postfix. I'm getting the following on "zmcontrol start":
Starting ldap...Done.
Starting mailbox...Done.
Starting antispam...Done.
Starting antivirus...Done.
Starting snmp...Done.
Starting spell...Done.
Starting mta...FAILED
postsuper: fatal: scan_dir_push: open directory defer: Permission denied
postfix failed to start

Starting stats...Done.
When I first restored I had a problem where it was using the wrong version of postfix, but I fixed that.

I've done zmfixperms (As root) several times.

Logs show the following error
zimbra postfix/postqueue[2554]: fatal: Connect to the Postfix showq service: Permission denied