It's certainly a good idea to understand how email works when you are running your own email server. I don't think setting up half a dozen services is the best way to get that knowledge though. Ideally, mox will explain some of it on its admin pages in the future. But I understand your point. Existing mail server components are long-lived, battle-tested, high-quality.
I wouldn't say internals of mox are obscure, it's all open source and relatively lean code (but clearly I'm biased). But indeed, if something goes wrong, you may not currently be able to google-search your way out of it. Mox is very young. The FAQ suggests first installing it a subdomain to gain experience, instead of switching your email over immediately.
FWIW, I implemented the mail export functionality before import functionality. You can easily get a tgz or zip with all maildirs or mbox files out of mox.