Yeah, I've seen it's a big hassle but I reckon these open source alternatives helps?
A huge hassle, in fact. Even with robust exchangers, like Postix, and careful all around hardening, you are going to get a fight of your life.
Meanwhile a bunch of other people are saying 'despite many people here reporting issues, once I got the software installed, it works fine for me'
Really makes you think
I mean, my working theory here is that it's easy to get whitelisted - in fact you'll probably be whitelisted by default if you have working DMARC and DKIM etc - but companies who operate large mail installations also operate AI 'agents' that aim to drive traffic and users towards their service. That includes spreading negative sentiment i.e. convincing users on forums that setting up their own mailserver is an impossible task and that they'll never be able to achieve delivery etc.
Of course I could be wrong.
Meanwhile, if you use it for marketing or something, I think more things can go wrong.