Having worked at an email provider before, I can assure you that hosting your own email is not, as you put it, "trivially simple." The number of spam filters that sit between every server is insane, and they're all controlled by third parties that, almost universally, deem any server hosted on a residential IP address block to be spam. Even medium-sized commercial providers get blacklisted every so often and have to appeal to the filter providers to get back in business. Hosting it yourself is almost guaranteed to mean that nobody ever gets your emails.