wilma@mail:~$ sudo -i
[sudo] password for wilma: 
root@mail:~# which postsuper
/usr/sbin/postsuper
root@mail:~# man postsuper
root@mail:~# mailq
...
18AEEFCBE8     2970 Mon Oct 17 20:14:02  MAILER-DAEMON
(Host or domain name not found. Name service error for name=merrillpjensen.com type=MX: Host not found, try again)
                                         root@merrillpjensen.com

-- 19 Kbytes in 10 Requests.
root@mail:~#  postsuper -d 18AEEFCBE8
postsuper: 18AEEFCBE8: removed
postsuper: Deleted: 1 message
root@mail:~# mailq
-Queue ID-  --Size-- ----Arrival Time---- -Sender/Recipient-------
...
6105EFCBD7     2970 Fri Oct 14 20:16:08  MAILER-DAEMON
(Host or domain name not found. Name service error for name=merrillpjensen.com type=MX: Host not found, try again)
                                         root@merrillpjensen.com

-- 16 Kbytes in 9 Requests.
root@mail:~# postsuper -d ALL
postsuper: Deleted: 9 messages
root@mail:~# mailq
Mail queue is empty
root@mail:~#