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How it Works: Email

In this month’s edition of How it Works, we demystify the mystery of instantaneous communication.

Nov 05, 2019

Have you ever wondered how email gets from your computer to your friend’s email moments after you hit send? Whether you're looking to write a paper about email or you're just curious to find out more about how it works, read on to learn all you ever wanted to know about email -- plus some facts that will definitely surprise your friends and teachers.

The First Email

According to the Guinness World Records, the first email was sent in 1971 by Ray Tomlinson. He was a computer engineer for a company named Bolt, Beranek and Newman in Massachusetts. They had a contract with the United States government to build a way to network computers that weren’t located in the same place so they could share information. The network was called ARPANET, which is an acronym for Advanced Research Projects Agency Network, and it eventually became what we now know as the Internet

While Tomlinson was working with other engineers on creating the Internet, he also had a pet project of his own. He wanted to find a simple way for two computers to send messages directly to each other. Before this invention, users could send each other messages over the same computer — kind of like if you were to leave a sticky note on the monitor of a shared family computer. It was also possible to send messages to numbered mailboxes on other computers,, but in order for someone to receive the message, it would have to be printed out and hand-delivered — kind of like getting a fax.

But here’s an interesting secret… Ray Tomlinson wasn’t the first person ever to send an electronic message! The first electronic message ever sent in the United States was actually a telegram. It was sent in New Jersey by Samuel Morse on January 11, 1838. His message was sent using electrical signals to a receiver using Morse Code — a series of dots and dashes that represent letters. It traveled across two miles of wire to reach its destination.

First telegraph Samuel MorseThe first electronic message ever sent was by telegraph using Morse CodeCourtesy of Still Unfold

Email Programs

To send and receive messages, you need to use an email program. The programs you use to send, receive and read emails are called “clients”. You can use a mail program or app on your computer, tablet, phone or watch to read your emails like Apple Mail, GMail or Outlook, or you can access your emails online through a web-based program, where you have to visit the client website to send, receive and read messages.

Tomlinson named his program SNDMSG. It was the first email program ever created! The first email he sent was from one computer to another computer in the same room. The content of that message has unfortunately been lost forever, but Tomlinson recalls it was probably just the letters across the upper row of the keyboard: QWERTYUIOP.

email clients and serversOnce email is set up on your device, you probably never think about all of the processes that take place every time you hit send

Configuring email -- the set-up

When you set up an email program, you have to tell the program how to send messages and how to receive them. It’s called configuring the program. Most clients (programs) make it really easy -- all you have to do is input your email address and password and it figures out the rest. The two major pieces of information that need to be configured are the server you use to SEND email, called SMTP (short for Simple Mail Transfer Protocol) and the server you use to CHECK email, called Post Office Protocol (POP or POP3) or (not as often) Internet Mail Access Protocol (IMAP). 

US Postal Museum 1968 story of a letterThis diagram was created in 1968 to show how a letter, now known as snail mail, travels from origin to destinationCourtesy of the US Postal Museum

What happens when you hit send

When you send a letter through the post office — or “snail mail” as it’s often called — you have to walk the letter down to the post office or hand it to your mail carrier. With email, once you hit send, it goes off to your email host’s Simple Mail Transfer Protocol (SMTP) server. For example, if you have GMail, the “post office” it goes to is GMail’s mail server. The email knows where to go because when you set up the email program on your computer, phone or watch for the first time, it programmed in — or configured -- the server’s name or IP address, and saved it automatically.

In order to send an email, you need the proper email address. Tomlinson (you may remember him from earlier in our story as the guy who made all this possible) is the guy who created the format of email addresses: USER@HOST, where the user’s name is separated by the @ or “at” symbol from the user’s location. 

The “host” is the server or email client. 

“User” is your unique name on that server. 

When you send an email, it goes from your host to the other person’s host. Each host has its own address book, called the Domain Naming System (DNS) and Mail Exchanger (MX) Record. When an email is sent to a host and its SMTP server accepts the message from the client, the computer consults the DNS MX to find the user name. 

Once your message is delivered to the other person’s server, the receiving server has to figure out how to route it to your friend. When you send a snail mail letter to a friend, your letter doesn’t go from your house to the postal carrier to their house. It gets passed along to the post office, the sorting facility, another post office, and then gets delivered by your friend’s mail carrier. Email behaves the same way. When you hit send, your email gets passed along through several internal servers before it gets to the recipient’s “mailbox”. 

Your email eventually ends up in a “mailbox” file or directory and stays there until your recipient checks their mail. 

how email worksThe journey of an email starts when you hit sendCourtesy of Webitblog

What happens when you check your mail

With “snail mail” the postal service delivers letters to your or house. To read the letters, you need to pick them up and open them. With email, if you want to read your messages, you have to use an email client to pick them up off the server.

When you click “Get Messages” or “Check Mail”, the program connects to the mailbox and downloads your messages using POP, POP3 or IMAP, depending on what your email client uses.

Once the messages are downloaded they show up as “new” or “unread” in your “Inbox”. From there, you can read, reply, forward, delete, or mark them as spam. If you choose to reply or forward, the cycle starts all over again! 

You've got mailThe first email ever sent over the internet was probably QWERTYUIOP

Have Your Say

Did this help you understand how email works? What’s something else you’d like to learn about — SPAM, the Internet, streaming video services, passwords? Tell us in the comments below.