How to flush the postfix queue

For some reason Postfix sometimes get stuck.
To see if there are some email stuck in the queue you can simply type:

oktober# mailq
-Queue ID- --Size-- ----Arrival Time---- -Sender/Recipient-------
38A1BF3B1*     1152 Thu Feb 12 00:22:39  www-data@oktober.momeunier.fr
                                         momeunier@gmail.com

-- 1 Kbytes in 1 Request.

Fortunately there is a little binary called postqueue that can help.

oktober# postqueue -f

to flush the queue (try to deliver all the messages)

More information on the man page of postfix