[conquistadog]

"Worse, the destination would say '250 OK' to every e-mail I sent them so I had no way of knowing that the messages had been sent to the big bitbucket in the sky. I got annoyed"

This. I go to a lot of trouble to follow all relevant RFCs, SPF, DKIM, DMARC, and TLS. My intent is to help other servers know I'm transmitting in good faith, I'm hopes I'll get the same fair shake.

If it's still not good enough for you, please at least let me know that fact, with a message I can investigate. At the very least, don't outright lie, which is what I take a bogus 250 to be doing.