When a registered user saves a search or favorites a property, they will get email notifications if there are any changes or updates on these properties or searches. Admins can click on the Subscriber Email Tracking tab and it will show you if the user has opened, clicked on or responded to these emails, this way, you can see which leads are the most active. This will also show you stats of all the emails that have been sent, opened, clicked on or reported as spam over the past 7 days.