Postfix Mail Queue Management

View mail queue

sudo mailq

Flush mail queue method1

sudo postfix flush

Flush mail queue method2

sudo postfix -f

Remove all mails in the deferred queue

sudo postsuper -d ALL deferred

Remove all mails from queue

sudo postsuper -d ALL

Reference: https://www.cyberciti.biz/tips/howto-postfix-flush-mail-queue.html