I may have found the problem but am waiting to hear from Marc on this.
I subscribed to a forum although I didn't post in it. That thread I got an e-mail notification from as it came in under subscriptions@, not blackhole@ . He's still working on it I guarantee you.
What you might have to do for now is uncheck the box at the bottom of the replies then use the "Subscribe to this thread" at the top of the thread for now and see if that works for you.