I've been self-hosting email for ~15 years, and have experienced many of the issues described. The biggest error in blackholing, that I never hear mentioned, i

I've been self-hosting email for ~15 years, and have experienced many of the issues described. The biggest error in blackholing, that I never hear mentioned, is that no mail server sending several hundred email per day is a spam server. If traffic is below a threshold level, several hundred or thousand emails per day, there is no way that server is part of a commercial spam distribution network. Small system operators should not be banned or blackholed in the same way as servers producing millions of email messages per day...