I just uploaded a new version of Email-MessageID with Class-Trigger support removed. How could I do such a thing? It just wasn't needed. You can subclass the module to get the same functionality, no need to use a trigger system. This also removed dependencies from what is basically a low-level module in the Email:: namespace.
So, in the name of simplicity and the middle name of efficiency, a feature was removed. Lets hope it works out.