Remove all emails for MAILER-DAEMON

MTA

Postfix

mailq | grep MAILER-DAEMON | awk '{print $1}' | xargs -n 1 /usr/local/postfix/sbin/postsuper -d

Mailq format

    4F12F2AC5A      322 Wed May 21 13:11:39  root@solman.toon-net.local
    (delivery temporarily suspended: connect to example.org[208.77.188.166]: Connection timed out)
                                             user@example.org

root@solman.toon-net.local = Sending email address user@example.org = Recipient