How can I get email notification for changes to site content?
This feature enables users to subscribe to be notified of changes to nodes or taxonomies, such as new comments in specific forums, or additions to some category of blog. All nodes also have an additional link that allows the user to change their subscriptions. Each user has a tab on their user screen to manage their own subscriptions. This functionality is also accessible via a link from the menu block. Users can use these features to set an auto subscribe function which notifies the user if anyone comments on posts they have made.
Administrative options are outlined here.