I logged into the zimbra admin interface and saw that the mta wasn't running correctly. So I logged into the server and did zmcontrol status. I saw that the mta indeed wasn't fully working. I followed this by a stop and a start.
When I'm stopping the services, I get this mail in /var/mail/zimbra.
Unable to determine enabled services from ldap.
Enabled services read from cache. Service list may be inaccurate.
When I do zmcontrol start, everything looks fine.
After sitting for a little while, I get this mail in /var/mail/zimbra.
postqueue: fatal: Queue report unavailable - mail system is down
When I do zmcontrol status, I get this:
postfix is not running
saslauthd is running with pid 31844