OK, that fixed it. Thank you!
No, it didn't actually.
I can now log into the admin panel, but when trying to connect as a user I get:
While trying to retrieve the URL:
http://mailhost.inc21.com/zimbra/
The following error was encountered:
* Connection Failed
The system returned:
(111) Connection refused
zimbra@mailhost ~]$ zmcontrol status
Host mailhost.inc21.com
antispam Running
antivirus Running
ldap Running
logger Running
mailbox Running
mta Running
snmp Running
spell Running