Push Server Error, Mountain Lion Server Mail unreachable (IMAP)

After upgrade from Lion Server to Mountain Lion Server. Mail still seems to be coming in, users just can't retrieve it.

mailaccess.log

Jul 30 09:08:39 server.domain.com push_notify[126]: getting GUID for user: _mailman, from directory

Jul 30 09:08:39 server.domain.com push_notify[126]: GUID: xxx, for user: _mailman, found

Jul 30 09:08:39 server.domain.com push_notify[126]: Warning: no device map found for: xxx

Jul 30 09:10:02 server.domain.com push_notify[126]: send notification: user: _mailman

I can't even create an IMAP connection from the server to itself, so there is no possibility of a router issue or ports issue etc. Also, I can connect to port 443 via telnet so I know the server is listening to that port. Thanks in advance.