I had similar problems with Gmail rejecting mail from my perfectly configured domain. I eventually gave up after finding, sometimes months afterwards, that an e

I had similar problems with Gmail rejecting mail from my perfectly configured domain. I eventually gave up after finding, sometimes months afterwards, that an email was not delivered (and when found within 30 days, it was always in the recipient’s spam folder). I eventually switched to fastmail (from a reputable, but too tiny for google to care about provider), and all the problems were gone. But ... I am almost sure the issue was that I had a catchall address cc:ing a Gmail address; not sure why that would trigger spaminess detection, but that’s the best I could reason with my data.