They must have read my nastygrams I sent them with every empty SASE they sent me begging for money,
If they are a BRM.. Business Reply Mailer, where they pay for the postage..... they have to pay for it, period... there is NO refusing it.
So if you use shipping tape and apply it to a cinderblock or something even heavier, they have to pay for that, which is a high postal rate.
As long as it is under 70 lbs. a customer over on the coast, was trying to get off some company's mailing list, and all the requests under the sun never got a response... so her best friend who was the local post master told her the above.....so her son had just bought new tires for his Toyota pickup, and had 4 bald 31 x 10.50 tires. She taped those BRM to each one, and had them shipped. Per each one postage was well over $50.
She got a scathing letter from the advertisers Company CEO, which she happily framed and put on the wall behind her desk.
She never got any more mailers..... you want to get off the NRA's and all of their advertisement.... try that... it'll work every time., and certainly gets their attention. I've done it myself by using a cinderblock....and it definitely worked.