Most services, including email providers, spam databases, and "ip-ban sites" have clear documentation, in terms of how to get on their good side, if needed, and it is often surprisingly straightforward to do so. Often it's as simple as filling out a relatively form.

They claim that, but everyone small I know who self hosted email has discovered that forms don't do anything. I switched to fastmail 15 years ago and my email got a lot better because they are big enough that nobody dares ignore them. (maybe the forms work better today than 15 years ago, but enough people keep complaining about this issue that I doubt it)

Have you ever tried to use it? Because I fought for about 2 months with both Google and Microsoft, trying to self-host my mail server, to no success. The only answer was amongst the lines 'your server has not enough reputation'. Even though perfectly configured, DKIM, DMARC, etc. Now imagine a business not being able to send a message to anyone hosted on Gmail or Outlook, probably 80-90 percents of the companies out there.

I feel you. I had my email on OVH for a while, but they handle abuse so bad that Apple just blanketed banned the /17 my IP was in. And I was lucky that Apple actually answered my emails and explained why I was banned. I doubt Microsoft and Google would give you any useful information.

> But running it is different issue. Notably, I have no idea, and have not seen a resource talking about troubleshooting and problem solving for a self hosted service. Particularly in regards with interoperability with other providers.

It's nearly impossible to get 100% email deliverability if you self host and don't use a SMTP relay. It might work if all your contacts are with a major provider like google, but otherwise you'll get 97% deliverability but then that one person using sbcglobal/att won't ever get your email for a 4 week period or that company using barracuda puts your email in a black hole. You put in effort to get your email server whitelisted but many email providers don't respond or only give you a temporary fix.

However, you can still self host most of the email stack, including most importantly storage of your email, by using an SMTP relay, like AWS, postmark, or mailgun. It's quick and easy to switch SMTP relays if the one you're using doesn't work out. In postfix you can choose to use a relay only for certain domains.

IME the communities around packaged open-source solutions like mailinabox, mailco, mailu tend to help each other out with stuff like this and the shared bases help. Maybe camp a few chatrooms and forums and see if any fits your vibe.