Right. You better not self-host like it's 1984 because that would also mean you're an open relay. And vulnerable for pretty much anything you can think of.
This config doesn’t make an open relay.
A typical config from 1984 is an open relay and vulnerable to the Morris Worm.
This config wasn't available in 1984.
Those wore the days :-) I remember playing on a University lab with half a dozen Unix workstations, sending an email with the path of server1!server2!server3 etc and hearing the email flowing from server to server by the noise of the disks!
Why are addresses not bang paths?
That's what I thought of when I saw the title, too.
Where are my ...killer!jolet! people at?
Ditto. I was sorely disappointed to click through "1984" to find a subheading on "setting up postfix".