I've been awake for the last 30 hours trying to fix my company email after a server crash reinstall and restore. I backed up and restored the entire /opt/zimbra directory using the method described in many different places.
Here are the lessons I have learned:
1. Zimbra for Fedora Core 7 will NOT run on Fedora 10 or 11! I did however get it to run on Fedora 8.
2. Install the dummy version of Zimbra first before replacing it with the backup
3. Kill the firewall.
4. Make sure sendmail isn't running.
5. Run /opt/zimbra/libexec/zmfixperms as root after restoring. But this IS NOT ENOUGH. Also run 'chown -R zimbra.zimbra /opt/zimbra/store'.
6. Make sure your domain is entered properly in /etc/hosts/
7. For unknown reasons I had to start ldap manually during the upgrade when I was getting error "failed with exit code 256.". Run 'ldap start' in a different terminal as the zimbra user when you get the error.
I hope this saves you from hours of pain and agony.