o_O
interesting name..
anyway(!), do:
telnet localhost 7071
ps -ef |grep mailboxd
see what they return. telnet should respond to 7071, and there should be a mailboxd process running. if not, check in /opt/zimbra/log/mailboxd.log/out to see if you can see some error (usually due to permissions or memory). if so, check your firewall and dns! |