@antekone and don't drop Gmail for an Outlook/Exchange Online system: they do exactly the same thing. Any SMTP server that is not run by an ISP or a giant mail hosting company is flagged as spam by default.
This is blatant anti-competitive behaviour, but they will claim it is for our own good.
The reality is that they want to control your data and lock you into the privacy nightmare that their ecosystems are.
It is AOL/CompuServe all over again, only much, much worse.
Instance perso. Principalement en français. Personal instance, mainly in French. Linux, OSS, Santé Mentale, 3615 MaVie.