This would be a great addition to the current event-based activation events of new message and recipient changed.
There is no great workaround in event-based activation other than:
- Polling in the event handler, which gives us a maximum of 5 minutes to react and defeats the point of having event-based activation and, without testing, I assume would not play well with multiple add-ons if we are not marking as "done"
- Have the task pane listen for these events, which means we then need to ensure a customer pins the taks pane for it to work
