@mandrake50 I went looking for an easier way to change email notification settings on threads and there's a simple method accessible from the subscription page. You can check the box next to the thread and then move down to the bottom of your subscriptions. There's a dropdown menu in the bottom left (almost hidden if you have a lot of subscriptions) that will allow you to change email notifications. I just made a few changes with my test account and toggling between on and off was simple. See if that works for you and stops the notification emails.
Note: it did take several seconds for the server to update and apply the change, so you might have to wait a moment or two while it processes the request.