Support the USPS by returning all 1st class junk mail with return envelopes back to the sender. The sender must pay for it to be returned.

The USPS gets paid twice for it

I've done that for YEARS, and, it's a great way to entertain children. You have them draw pictures, write "no thank you" on the offer, etc., and return it in the pre-paid envelope. Save every scrap of paper from that junk mail, and cram the envelope full -- including folding up the envelope it ARRIVED in. The children like having "very important mail to send" and it helps control all those drawings you really don't want to keep forever. "Please draw a picture for XYZ Company, telling them no thank you."

Be sure to remove identifying data.