sure there is an email notification (it's buried fairly deep though)
Up the top right of the screen it should say
"Welcome (username)" "view your profile"
Well click on "view profile" - on the next screen (at about the same location - top right) there should be 3 options "Profile - Edit - Favorites"
Click on "Edit" and there will be an option on the next screen.
Notification by e-mail - Send me a message when a new entry is posted in one of my favorites.
If you enable that, an email will be sent when someone replies to your "favorite" topic .
You add topics to your favorites - towards the top left of each topic screen.
You manage favorites from your profile screen (remember those 3 options - Profile/Edit/Favorites ?) - or click on the '?' next to "add to favorite" on the topic screens.
Naturally - you can also subscribe to your "Favorite" topics via a RSS feed.