It was a while ago, if I recall correctly the block seemed to be ip based (it reported my ip not domain-name). I host with vpsdime, while it is a vps and thus to be expected I don't seem to be on any other lists.

DMARC, PTR, no open-relay, encryption, etc., all set up on my end. The email I was trying to reach was in fact an (important to me) gov't adress. Ended up using my old gmail for that instead.