Deleting a message from the Postfix queue

The postsuper command has an option to delete Postfix message queue files. To delete the message with queue id ABCDEF, perhaps obtained from mailq output, one would use:

# postsuper -d ABCDEF

To delete a large number of files one would use:

# postsuper -d - < filename-with-queue-ids

To delete all messages in queue:

#postsuper -d ALL
http://www.postfix.org/faq.html