I returned all of these envelopes filled to the max with random pieces of junk paper. BUT, I made sure that my name and address (or zip code) did not appear in anything that I sent back. If I understand the USPS rates correctly (https://pe.usps.com/text/dmm300/Notice123.htm), each returned mail costs them $1.38. Maybe if enough people sent these envelopes back (with junk), the low hit rate compared to cost of the returned letters would make this business unprofitable.