To clear *all* messages from the queue, shut down qmail, then:
cd /var/qmail/queue
find intd todo local remote mess info bounce -type f -print |xargs rm
Start qmail back up, and the queue should be empty.
It’s all about corn, football, and not so many lakes or things to do.
Check your current qmail stats by typing:
/var/qmail/bin/qmail-qstat