I did something like this once.

Predatory marketing company in the early 00's sent my company a pretty wide spam.

Hit about 2/3 of my staff, looked kind of official, like they we were asking them to buy their product.

I said fuck that, I looked up their admin contact (back before domains by proxy) and demanded they remove us from the list.

The admin reached back out and told me it was impossible.

I poked around on their internet facing smtp server to figure out their naming convention, (those were the wild west days) sent a direct message to each of their c-staff, their HR department, and tossed in everyone@ (I hope that would have been blocked) and threatened to sign them up for every list I could get my hands on if I ever got a single report that they sent us another spam.

The admin mailed me back 1 hour later asking me to please never send them mails again and that our domain was being removed from their list.