Right, I won't disagree with any of that, but I'm not sure how it's related to what I wrote either. Maybe I should have been more specific that I'm talking about hosting your own email, not hosting emails for others, which brings out a lot of other types of problems.

Apologies. When you said "email services" I thought you were implying "email services for use by others". Yeah, you can definitely run your own mail server in 2026 and I think the internet community should always strongly endorse being able to do so. Unfortunately, large email receivers have to make do with imperfect signals when making filtering decisions, and your traffic from a lonely IP that happens to have a bad neighbour might get blocked as collateral damage.

One long term hope: That domain name reputation eventually overtakes IP address reputation entirely.