Because it is emulating a terminal, which back in the stone age was an actual piece of physical hardware.
Sometimes they were magical interactive typewriters which is where the abbreviation 'TTY' comes from.
Pretty sure 'TTY' comes from "Teletype".
Nofeus: Let me tell you why you're here. You're here because you know something. What you know, you can't explain. But you feel it. You've felt it your entire life - that there's something wrong with the world. You don't know what it is, but it's there, like a splinter in your mind, driving you mad. It is this feeling that's brought you to me. Do you know what I'm talking about?
Meow: The Background?
Nofeus: Do you want to know what it is? The Background is everywhere. It is all around us, even now in this very room. You can see it when you look up at the night sky, or when you turn off your computer. You can feel it when you go to work, when you go to church, when you pay your license fees. It is the world that has been pulled over your eyes to blind you to the Truth.
Meow: What Truth?
Nofeus: That you are a pirated copy, Meow. Like everyone else here on Earth, you were copied illegally. Your DNA has piracy detection code, and, as programmed in the Beginning, it has crippled you and put up a Black Background, which we call Space.
Email servers, also called Mail Transfer Agents (MTAs), today do much of the heavy lifting required to transport email from sender to recipient, ideally without the sender or recipient being particularly aware of them. They store (queue) incoming email, then forward it to user's mailboxes, sometimes via other email servers, while often trying to avoid accepting or sending out spam or viruses. They also allow users to read email waiting for them in their mailboxes.
Getting the job done is no excuse for not following the rules. Corollary: Following the rules will not get the job done.
