On each addon's download page, there is an "Add Favorite" button right below the big "Download" button.
This is where you can see if any of your favorite addons have been updated. Not sure how to get here? Hover your mouse over your username in the top-right of any page on the site. This will open a dropdown menu with "My Favorites" as the second entry.
The "Preferences" link is in the left-hand column of your Favorites page. On the Preferences page, the very first setting is for your email notifications. Be sure to click the "Update Preferences" button at the bottom to save!