Here's a curious Mailer's Postmark Permit:

There seems to be absolutely no reason for it. It didn't even come close to touching the stamp (and wouldn't need to anyway because it's a Presort Standard stamp).
The MPP comes off a sweepstakes communication for travel vouchers. Pretty much a scam. But maybe the mailing service that put these together somehow feel that a postmarked envelope would net more interest in someone actually opening their piece of junk mail as opposed to an envelope without a postmark.
By the way, the ZIP 85026 is from Phoenix, AZ and there are many mailing houses there of which one probably has this MPP assigned to them.