This Knowledgebase article provides information about testing to ensure services are running.
A component of the product includes monitoring which provides the facility to monitor many services. For example, Neverfail for Exchange includes SMTP, processor utilization, memory utilization, etc. The monitoring capability can determine if a service has failed, and based on the parameters set by the administrator, can take corrective action on failed services. In this case, Exchange can appear to be available, but may not have all services functioning properly.