As I don't come on the forum very often now, it would be a good feature to have a notification by email of any Private message awaiting your attention and possibly a link with in that email which takes you straight to the PM.
We had this feature in the past, it would be nice to see it back.
If I am understanding you correctly ...your request is possible by clicking on the bell icon in the upper left hand corner of the thread you are interested in receiving email notification from. That's what I do to keep up with threads that I want to follow.
You will receive an email every time someone adds something to a forum thread .. like this one. Hope this information was helpful.