Subscribing to the topic or email notifications

Hi,

We installed and are using the forum, but no one is being notified of new posts being made.

We have the setting on for the admin to be notified, and I think they are, but the users are not being notified when someone responds to their topic or thread.

I was under the impression that the forum should do that. ANy ideas where to start to try and track this down?

Thanks!

CJ