They definitely have anti spam. It's great at triggering on emails from a self hosted email server.
I've been maintaining one for a few years and have pretty good deliverability. 95% of the time when there's an issue it's Outlook/Hotmail marking me as spam. And no I don't do email marketing or newsletters.
Yeah, love all the innovation and competition in the mail clients nowadays.
You sell your data to big companies or you get spam blocked by these companies, if you self host.
Why google would invent better email sender validation procedures and encryption, if the current system works pretty well for them.
I've been maintaining one for a few years and have pretty good deliverability. 95% of the time when there's an issue it's Outlook/Hotmail marking me as spam. And no I don't do email marketing or newsletters.