Steve wrote a while back about how Mailchimp handled his complaint.
Sadly, I have a counter example from recently.
You’ve got a customer hitting an address they bought from someone selling really old lists. This entire domain was retired more than 5 years ago, and laura-info@ was never used to sign up for anything.
I sent it to abuse@ the ESP because I thought it might do some good and that the ESP in question wouldn’t support spammers.
The response I got was that I had been unsubscribed. Their abuse desk person also assured me, “We have a no tolerance for the sending of unsolicited mail, and we will not allow this sort of behavior to continue.”
Except, this is actually the second time I reported this spammer to this ESP. And the spammer is still spamming through that ESP.
I really don’t care if ESPs actually let people spam through them. If they want to do that, fine. But, don’t tell your abuse and compliance staff to tell people that there is a no tolerance policy for spam. Seriously, this mail is unsolicited. It was unsolicited in July when I reported the same customer to you. And it will be unsolicited in 3 months when your customer decides to add my address back to his list again.