[pflanze]

I don't think vbezhenar necessarily does anything wrong. I've been (and still am?) running into the same issues with Gmail, as well as with Yahoo (but not any other providers). I'm owning domain and IPs for about a decade, using reverse DNS, DKIM, SPF, on no blacklists, also using SRS for forwarding, registered the domain with Google, not bouncing possible spam, older recipients who moved mail out of spam folder: no problem, new recipients: tagged as spam. I'm using my mail server for a few small-volume mailing lists now, with an added comment on the subscription instructions that subscribers should watch out for mails moved to the spam folder; that has been working well enough for over a year now, but I'm not sure whether that has helped alleviate the problem (I should do a test run again, but it's time consuming and worrisome to create new Gmail user accounts for testing as I fear Google linking those accounts to myself might actually contribute to the bad scoring).

I know someone who does his own mail and does less than me (e.g. no SRS), and yet he doesn't have problems and thinks I'm doing something wrong...

My best hypothesis is that Google doesn't like the network that my server is in (Hetzner, various neighbours in the network are listed on a couple blacklists). When I find the time I'll set up a server with a different provider and see if it improves things. Other hypotheses are the software used (buddy uses OpenBSD and its mail server instead of Linux and QPSMTPD/Qmail+patches, perhaps they care about software headers or are doing OS fingerprinting), the fact that I'm using a fallback server on another continent (US), network timings, and plain noise (perhaps they use some kinds of machine learning that have persistent low-level irregularities).

PS. yes I'm not doing DMARC yet, but neither does my buddy.