As Thorsen said there are some SF notification changes being made now.
You can opt in to get notified "online" for new posts to your subscribed threads.
Take a look at post #2 from John (z3r010) in
Right now I'm getting Email and Online notifications for new posts.
Enabling the online notification may help you until your email issue is resolved.
If there is an issue, I think John would want to know so it can be fixed...