I don't buy into the myth that running your own mail server is "hard".
For a server with only a few users, the hard part is outgoing mail, ensuring your mails get delivered. I did what I can here, and simply use a paid service on another domain for important things where delivery must be "guaranteed".
It's an interesting post, but saying it's "not hard" and then "welllllll it's not hard if you don't bother with a spam filter & pay a professional company for 'important' email" is pretty misleading.