I have indeed configured my mail server. Maybe it's my bad choice in server software (Exim), but setting it up (also for receiving messages and exposing them using IMAP) was really not hard[1]

The Exim that comes per default in Ubuntu server has a default configuration that works as an SMTP server for a web application - no tweaks needed.

As I said: Your SMTP server needs two things:

1) You need an IP address in good standing. If you don't have that (if you are on EC2), you might need to sign up for an SMTP service (or sendgrid, but my concerns of using a nonstandard JSON API over the SMTP standard still stand).

2) If you have an IP address in good standing, you need a valid PTR record. You probably can't do that for yourself (unless you have an octet on your own or your provider goes really great lenghts), but all providers I have dealt with set this up for you no questions asked and without charging extra.

Then, getting the mail through through spam filters closer to the users is another problem, but Sendgrid wouldn't help you there either as this is largely dependent on the content of the email (and maybe a header or two like Message-ID).

1) http://www.pilif.ch/mail.txt is documenting the configuration. It's based on a newsgroup posting in 2001 - and it's in German.

Later on, Oliver Siegmar took my configuration and built http://www.xams.org/pages/home/home.php

This configuration plus the PTR record have lead to a configuration that is sending out 10000s of messages per day and we never had a blacklisting or spam filtering incident.

> 1) You need an IP address in good standing. If you don't have that (if you are on EC2), you might need to sign up for an SMTP service (or sendgrid, but my concerns of using a nonstandard JSON API over the SMTP standard still stand).

You only need the JSON API header if you want to use their "apps". If all you want is to send simple emails you can just use their SMTP server as a real SMTP server.

In addition to this, once I get a mail server running, I'm terrified to make changes lest incoming mail end up in a black hole. One time when I made an incorrect change, the backup mail server that godaddy "helpfully" put in my DNS settings started bouncing everything coming in. Even in the absence of a broken backup server, my experience has been that errors in the process are too frequent and take too long (on the order of minutes) to discover.

How true. Very recently I tried to setup SMTP for intranet and gave up 2 days after. There is just no simple enough guides. Most of them make assumptions of my knowledge, when I had 0 of DNS/SMTP servers.