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