You can manage these from your Account page or Account menu:
Main Notifications allows you to turn on or off whether you want to receive an email when a friend or favourite member (fave) makes a post.
My Notifications allows you to turn on or off whether you want to receive an email when one of your posts is commented on or rated.
In both cases, you can choose whether to be never notified, notified immediately, or to receive a daily, weekly or monthly digest.