As root user execute:
/opt/zimbra/postfix/sbin/postqueue -p | tail -n +2 | awk 'BEGIN { RS = "" } / sender@mail\.com/ { print $1 }' | tr -d '*' | /opt/zimbra/postfix/sbin/postsuper -d -
To Delete ALL Messages From Queue
/opt/zimbra/postfix/sbin/postsuper -d ALL
or
/opt/zimbra/common/sbin/postsupe -d ALL
Another way to do this:
mailq | awk '{print $1}' | postsuper -d -
To Delete ALL Messages From The Deferred Queue
/opt/zimbra/postfix/sbin/postsuper -d ALL deferred
To Delete ALL Messages From The Hold Queue
/opt/zimbra/postfix/sbin/postsuper -d ALL hold
There’s a nice Zimbra wiki page with detailed on cleaning up mail queues.
https://wiki.zimbra.com/wiki/Managing-The-Postfix-Queues
