[xantronix]

Sure, it's a pain in the ass, but why should we scare people away who WANT to self-host?

Pro tip for people with low mail volume or those who can spare a few packets on extra DNS traffic: Validating that a host has a non-provider PTR record which has corresponding A/AAAA/CNAME records resolving back to that same IP address, is enough to filter out a large bulk of spam.