Favorite thread
You can add boards and threads to your favorites. On the bottom of a board or thread there is the link to add or remove your favorite. You will then receive a notification e-mail in case of new posts or threads. Only one e-mail will be send each favorite. So you need to visit the board or thread in order to get new notification e-mails.
Within Edit Profile » Management » Favorites you can get an overview about all favorites. You can also remove them from your list.