The first few I crammed full of the entire set of garbage they sent me with a message printed in very large black Sharpie letting them know I didn’t want anything to do with them. That was 50+ pieces of mail ago. I’m happy to let them waste their money sending me cr@p that I promptly shred. We’re planning to acquire a cat soon and when we do, I’ll use their mailings to line the bottom of the litter box.
Hope you don’t mind cleaning up crap then. Some cats are mighty fussy about where they drop their load.