I run my own servers. They’re on a VPS so I can empathize with folks when their mails get blacklisted because their server is on the CIDR range as some offender.

When I get repeat, bad spam that manages to sneak past my DKIM filters I generally reach out to the ISP that originated the messages and report the abuse before I report to the blacklists. Admins are generally quick to respond.

The problem is the spammers, scammers, blackmailers, etc. And maybe the domain registrars who enable them and anonymize them a little bit.