Sun Java System Messaging Server 6.3 Administration Guide To Monitor the Size of the Message Queues

Probably the best way to monitor the message queues is to use imsimta qm and imsimta summarize. Refer to 27.8.6 imsimta qm counters.

You can also monitor the number of files in the queue directories (msg-svr-base/data/queue/). The number of files will be site-specific, and you’ll need to build a baseline history to find out what is “too many.” This can be done by recording the size of the queue files over a two week period to get an approximate average.