waitlist for events- after register expires but still time before the event

Auto-register is fantastic, but when auto-register hits its time limit have the system send an email to all waitlisted players (like it does if auto-register is not turned on) to let players know a spot opened up and to register if they want it.  This would be super helpful when we have late cancelations but don't want to auto-register since the timeline is too tight to assume a player could make it.