1. To see the mail queue:

mailq

2. To flush the mail queue:

postfix flush

or

postfix -f

3. To remove all mails from the queue:

postsuper -d ALL

4. To remove all mails in the deferred queue:

postsuper -d ALL deferred

5. To delete all queued messages from or to the domain called webserverpage.com:

./postfix-delete.pl webserverpage.com

Note: You may download the script on the link below.

http://blog.webserverpage.com/?p=541

6. To delete all queued messages that contain the word “virus” in the email.

./postfix-delete.pl virus

7. To know the number of messages sitting in the deferred queue:

find /var/spool/postfix/deferred -type f | wc -l

8. Sort user email accounts with corresponding number(s) of email.

mailq|grep ^[A-F0-9]|cut -c 42-80|sort |uniq -c|sort -n|tail