In the US, companies are under no obligation to honor any request that they stop sending you physical mail. Send them as many requests in as varied a format as you like; they can ignore each and every one.
EXCEPT. If you say "please stop, this mailing made me horny", they are required by federal law to immediately block your address. It doesn't have to be honest or sincere; just saying "your ad turned me on, and I don't like it" is enough. 🌈⭐️