I wanted to configure email alerts from our Brightmail gateway (formally Symantec 8300 series appliance) so that we would be notified when message queues were over certain thresholds. This is a missing feature on the appliance, so as a workaround I've done it using Cacti instead. We already monitor CPU and memory usage of the appliance using Cacti by configuring it as a 'ucd/net SNMP device', and this week I discovered Symantec also publish templates for Cacti for graphing MTA queues (inbound, outbound and delivery). There are 2 graphs, one showing number of messages, and the other showing the MTA sizes in megabytes.
I added the templates to our Cacti and configured them against our Brightmail gateway and they work very nicely.
Queue sizes as graphed by Cacti
Just to explain the queue above - we always have a fair amount of transient garbage stuck in the delivery queue due to malformed domain names, typos in email addresses and other random stuff stuck in a retry queue for a few days.
For alerting we already have the threshold plugin 'thold' installed on Cacti so I set up 2 new threshold templates for the inbound and outbound delivery queues. If a queue now goes over 150 messages we will receive an alert - it will also send an email when the value goes back under the 150 value.
The email alerts also contain a copy of the graph as an attachment which is a very nice feature. It pretty much tells you what time your queues started building up, and this is a valuable clue in helping you find out what has caused the problem.
