Check manual page of qmail_stats
Length of the qmail Mailqueue
This check uses the output of qmail-qstat as sent by the linux agent of
Check_MK. The command lists all mails which wait in the mail queue.
This check creates one service per host which represents the state
of the servers mailqueue.
The check will result in WARNING/CRITICAL states when the number of items
in the queue reach the defined thresholds.
On each system which provides the qmail-qstat command one service is being created.