I think I agree with you (RE: make a comprehensive write-up), but I also seem to remember thinking the same thing when I was setting up the latest iteration of the server and then googling it and finding that such a guide already exists :) Part of the problem is that it's an evolving system and things change over time.
Spam is an interesting problem. Assuming one self-hosts and makes their email address publicly available, then one can get a metric for how much spam is flying around. Eventually one will try to stop spam from coming to their inbox, and on doing so one might build a mental model for how the big mail providers combat spam and realize why one's emails are not being delivered. Then one might realize that one is sending mail that one would not willingly receive! And then take action to resolve.
In general though, there is some base effort to establish trust, and as long as you don't ruin it by sending spam, then you shouldn't end up on a blacklist. If you find that your IP was on a blacklist before it became yours, then work with the people that are blacklisting - but at that point it does become a bit of a job. I actually ran into an issue in my professional life where an AWS WAF rule started alerting on one of our own servers hosted in AWS because someone had previously used the IP for malware C&C.
Anyway - I will think on this and see if I can write something up. It's a good idea. My main concern is that there is a gap between the way I did things (sysadmin style) and the "new" way of doing things (containerized).