Unfortunate reality. I stopped self-hosting after many years three or four years ago. Keeping up with the requirements to stay out of the spam bin was too much work, and the risks of non-delivery were too high.
Remember, even if you have everything 100% nailed down with SPF, DKIM, etc. you can still end up on a random blacklist, some of which are basically extortion shakedowns. Now, you can say, "well ignore those losers, who cares?" but sometimes you have a customer who directly or indirectly relies on those blacklists. I certainly do, that's how I found out!
Remember, even if you have everything 100% nailed down with SPF, DKIM, etc. you can still end up on a random blacklist, some of which are basically extortion shakedowns. Now, you can say, "well ignore those losers, who cares?" but sometimes you have a customer who directly or indirectly relies on those blacklists. I certainly do, that's how I found out!