In-text @Username reference to send notification to user

Hi there,

On the Herocraft website which uses Xenforo, if you type in @<username here> (example: @Footie), it will turn the name into a blue link and send the user (in this case Footie) a notification which links them to that post. This is a great way for members to direct admin attention to a particular thread.

I searched and searched through the add-on's forum but didn't find anything. Does anyone know where I can get a hold of this feature for my Xenforo site?