Simple Machines Forums (SMF 2.x) makes it easy to get notified by email whenever there is a new post to a board.
Simple click on a board and click the “Notify” tab and you are instantly subscribed to that board, meaning you will get email whenever there is a new post or reply.
While there is currently no universal option to enable email notifications for the entire forum all at once, clicking the “Notify” tab in each board is an easy workaround.
Update: here’s a cool way to Auto-notify Members When Topics they participated in are Updated
These email notifications are available for administrators, global moderators, and any registered member unless you changed the settings otherwise.
For additional options on getting email notifications, click the Profile tab, then go to Modify >> Notifications in there you have other options about when you are emailed by the forum.
Remember emails from the forum will come from whatever address you have as the Webmaster email in the Admin area under Configuration >> Server settings.