You may use the "Forums" link of the left of the home page, or at the top of the page when you are in any forum to get to the Forum overview page. While there, you should notice a column of yes or no on the right of each forum. Clicking on this response will change it from where it is set. A yes response will cause you to recieve an email any time a new post is added to the forum, while a no response will not alert you to any action in that specific forum.