Here is a very handy script that delivers a report which contains health status about transport queues, services and DAGs. It even does a simple mail flow test. It requires only a few parameter changes and then can be run as a scheduled task. Although it isn’t a substitute for real time environment monitoring, it at least gives a quick view of the environment health.
http://exchangeserverpro.com/powershell-script-health-check-report-exchange-2010/
All Things Exchange 