Canvas Decision Rule On External Activities

Hi All,

We use External Activities for physical and live webinar attendance.  One could be set to Attended, No Show, or Walk In (physical event only).  We want to send post-event emails to these folks and have the ability to send one message to the folks that attended and another message to the folks that did not.  From what I can tell, I don't see any ways on the canvas to set up a decision rule using External Activities to fulfill this requirement.

Is this even possible?  What do other folks do?

We know that we could upload the attendance data to a CDO and then use that, but we only want to upload to External Activities.

Many thanks,

James