Right now only hotmail bounces mail. Am using DO/Singapore. Other centers fare better.
My server is a "Mail-in-a-Box" running on a DigitalOcean VPS.
That way no one reads the emails sent to you and the ones that you send get through (and outbound privacy is not expected if you are sending to gmail or another provider anyhow).
That also makes it harder to track conversations and would take manual work to recreate the conversation threads.
Excision Mail which runs on OpenBSD hits the majority of what you need technically. https://github.com/Excision-Mail/Excision-Mail
The bigger problem is finding a hosting provider that hasn't had their entire space blacklisted.
For that, you're likely going to have to pick a "responsible" provider, have a couple of rounds of back and forth with them to prove you're neither an idiot nor a spammer, and ask them to manually open the port for you. And they're going to demand something that will tie to identity.
This is completely not true. Comes up every time there is a thread related to email. Every time many of us who host our own email servers will explain how it is not true. You can absolutely self-host your email server for your domains, configure it correctly and it will work fine.
gmail has a huge false positive spam identification problem, but it applies to all emails, even those from gmail to gmail.
From talking to other people who tried the same, my theory is that the main reasons for my success were having everything configured well from the very beginning, running on a single static IP for multiple years, hosted at reputable mid-range server provider (not the cheapest, not the most popular) and not sending any "broadcast" email whatsoever for a very long time.