If you want people to clear out massive amounts of unread emails, don't do rewards points.

Figure out a way that I can select a date and only remove all unread e-mails from before a certain date. I would love to delete 23k emails but I'm not spending 12 hours doing it.

Also, make sure that it won't delete read messages or any e-mails that are sent from personal accounts versus accounts with "unsubscribe" at the bottom.