We are a relatively small company and we operate our own mail server, mostly out of a shared belief in data privacy among myself and our staff. We self-host mo

We are a relatively small company and we operate our own mail server, mostly out of a shared belief in data privacy among myself and our staff. We self-host most of our tooling (mail, internal chat, Gitlab, CI/CD, and so on). It turns out this is all pretty simple given modern virtualization infrastructure and, in my estimation, has many upsides versus the alternatives. That said, like the OP, despite having DKIM, SPF, proper DNS, and every other measure applied, it's conceivable that gmail might reject some emails from us. I don't have any memory of that actually happening, but I have heard stories like the OP's several times. It's a fairly common topic in conversation forums about self-hosting email servers. I don't expect the situation to change any time soon—I don't expect Google to change their ways and it would require significant pain for me to surrender to the gmail hegemony.