You know why you don't realize this?
You self-host stuff you barely use, yourself, and that nobody else uses. You're not self-hosting something used by entire groups of people.
Discussion
I self-host email server to be able to manage it actually, I can't trust a 3rd party with it
I loved self-hosting my email server but at&t, and their shenanigans, made it a nightmare to maintain. I recently moved to purelymail.com real easy to setup and very affordable. Would recommend 🫡
What shenanigans are yoy talking about? If you are referring to their spam filtering, they are pretty responsive at their abuse_rbl email.