Status and alarms from external email alerrts

In the environment I am supporting we have some custom applications that only support sending of e-mail alerts instead of SNMP traps. How can I take the received email alerts and have Icinga read them?

My approach would be to feed them through procmail or similar, pipe them into
a script, and convert the content into a passive service check result which
you feed into Icinga.

Antony.