Check manual page of nullmailer_mailq
Length of the nullmailer mailqueue
This check monitors the number of deferred mails in the outgoing mail
queue, as sent by the linux agent of Check_MK.
This check creates one service per host which represents the state
of the outgoing mailqueue.
The check will result in WARNING/CRITICAL states when the number of items
in the queues have reached the defined thresholds.
On each system which provides the nullmailer-send command one service is created.