I am working on a new service offering that would check a company's email service every 5 minutes or so by sending an email to an address ie. emailautoreply@abcco.com to make sure it is sending and receiving properly.  If my server doesn't receive an autoreply within X minutes, it will notify our staff who will call someone to check out the problem.  Who is already offering a service like that? Is there a name for it? I have searched google and can't find anything out there.
Web service that verifies email availability/uptime?
email