Monitor solution can be used to alert and send emails when servers go offline/crash/shut down. This is done by creating an Agentless Monitor Policy that uses the ICMP Availability Status metric, which causes a Remote Monitor Server (RMS) to ping other servers on a constant interval and alert when a server becomes unresponsive. Keep in mind this can result in false positives when servers become too busy to respond to pings.
Altiris - ITMS 8.x
Create an Agentless Monitor Policy
Add a Metric Rule
Target the Policy
Add an Email Action (Optional)