Question : Email Dead Man's Switch or Heartbeat monitor

I'm looking for a service that can monitor our email server. Specifically, I'm looking for a service that will receive emails that our server sends out and then trigger an alert if it fails to receive an expected message.

Let me explain the situation a little more fully. We have a server that is critical to our business operations. There are any number of error messages and monitoring alerts that the server will send out when something goes wrong. But, all of these are predicated on the idea of the SMTP service working. If that service fails then no error messages are sent out.

So, my idea is that I write a script to send a heartbeat message every 5 minutes or so. The destination would be a 3rd party server that knows to expect these messages. If there are a given number of consecutive missed emails then that monitoring server would start sending out alerts to email, pagers, cellphones, etc.

Does anyone know of a service that could do this? Thanks for your help.

Answer : Email Dead Man's Switch or Heartbeat monitor

I attach overview of DNSAlert.  This software prods your mail server at regular intervals and warns you if there any changes from PASS to FAIL occur.  The tests are configurable so that you can ignore whether your website is up, or not for example.

DNSalert.pdf (2.1 MB) (File Type Details) 

DNSAlert overview