In my experience self hosting email it has pretty much been “set it and forget it”. I feel like there’s a lot of fud from people with misconfigured email servers (because there is a lot that can go wrong on setup). In every case I’ve seen where people are complaining about email deliverability I’ve found that they haven’t configured DKIM or rDNS properly. That doesn’t mean there can’t be issues, and I am sure it is technically possible to get sent to oblivion, but I feel like this issue might be somewhat overblown.