Just like other MTAs, Postfix stores mails in a queue to process them for sending. For whatever reason, one may want to delete a particular mail from the mail queue.
Using Postfix’s postsuper command, you can easily accomplish this task.
To delete mail from mail queue, you require its ID (mail id). This can easily be obtained by running the mailq command:
You can now delete the mail by issuing the command: postsuper -d MailID where MailID is the ID as shown above.
To delete all the mails in the mailq, use the command postsuper -d ALL .