As an alternative: install Mox and do as the installer says.

Seeing up your own mail server is too hard, particularly if you don't use one of the easy ways.

As someone who hosted it for a very long time - don't. Not worth the effort, it's a huge pain.

Great learning lesson, but very frustrating (IP reputation is everything, blocking spam is beyond hard)

Not saying I don't appreciate the write-up but I wish they titled it "send-only".

While setting up your own e-mail server is like pulling teeth there are still plenty of people interested in doing it anyway... and I could see it being really annoying if you thought you finally found /the/ guide only to be let down once again.