Earlier quoted context omitted.
I've never had any problems with mail delivery and I've never paid anyone a dime. I even violated one of rfc-ignorant's rules (a fake tertiary MX record) and still didn't get blacklisted :) There are no internet authorities that control mail delivery, either, BTW. Many sites use heuristics to control mail acceptance, however, including third-party whitelists and blacklists. It can suck if you get on a blacklist, but…
Hrm. Perhaps it was a certificate issue with SSL which the guy uses on his mailserver? I'm really not up to speed with configuring much beyond msmtp. In any case, from a decade of listening to the random things he's had to deal with, I certainly have to agree with your final comment.
I think there are probably some MTAs that will STARTTLS for normal SMTP connections, but again, I've never heard of anyone using SSL/TLS as a spam-filtering criterion. (I might look through my old logs to see if anyone other than me ever issued STARTTLS on my mail server. But I'm guessing the number was near zero.)