As someone who created a reasonably popular SMTP server you basically just listed why it's hard. That plus the problems of sending (ever end up in a blacklist?

As someone who created a reasonably popular SMTP server you basically just listed why it's hard. That plus the problems of sending (ever end up in a blacklist? It's not fun). Setting up a mail server is often worth it, but requires experience that about 0.01% (being generous) of the developer community has.