Comment by dankai

This is a great guide but from my experience, even if you configure it 100% correctly, email services like Gmail may still classify your emails as spam for no apparent reason while not being on any IP or domain blacklist. I tried for hundreds of hours to get around it with no avail, and my emails to Gmail always went to spam unless it was a response to an email from a Gmail address. Had to go back to a 3rd party hosted service (iCloud) because of it.