email event question

Hello, I created a plugin that executes on email create.  This plugin is getting called when I send an email because I can validate that the expected data is getting created.  However, when the system receives an email, this plugin does not appear to get called, because the expected data is not created.

I haven't had time to investigate this behavior but does this scenario seem unlikely?  In other words, should I expect that CRM will always trigger the email create plugin when an email is received?  Or do I need to wire up a plugin to handle a different email event for received emails, because received emails don't trigger the email create event for some reason?