Can you explain what you meant about the tech? I am actually curious about hosting my own email. I think what I was referring to was the first reply on HN. Specifically this comment:

"The primary issue brought up is deliverability. If you don't have a static IP, or you don't have control over your reverse DNS PTR, or the reputation of your IP is poor, then pay a company to smarthost your outgoing mail through them. It's a few $ a month, and poof! Problem solved.

By that "logic" self-hosting is easy because I could have a third party handle outbound AND inbound mail, which is essentially standard mail hosting with a custom domain.

Plus you cannot just turn-key create a high reputation, you start out with low and your emails will be dropped into spam."