If what I suspect is right, a lot of these notifications were queued up for some reason, waiting to send. Greg read the previous PM but now the notification that he got the PM is just coming through.
I would want to see that going forward, there is no delay in getting notifications for PMs, subscription threads, etc. In fact, I'm getting notifications routinely now for PMs that I just now received. I can change that setting so that I don't get emails for PMs.
So backing off to the stun setting seems to work!
How are we all making out on this? It's really necessary for us to have feed back before we can go further.