How to delete Directadmin Mail Queue with SSH
The Mail Queue will show you, of course, all the email messages that are in the queue. If a user on your server has issues with the emails then you should check the DirectAdmin Mail Queue.
To remove all mail queues, just with one single command.
exim -bp | awk '/^ *[0-9]+[mhd]/{print "exim -Mrm " $3}' | sh