SciTech

Emails have secret lives in behind-the-scenes delivery processes

Credit: Justin Lin/Staff Credit: Justin Lin/Staff

Email is a versatile tool often accused of replacing the postal mail system. But exactly how does this technology work?

In its very early stages, email was simply a text message sent from one place to another, similar to telgraphic communication. In fact, Morse code telegraphs could be classified as ancestors of email from the 1930s.

In 1960, when computers were enormous, the Massachusetts Institute of Technology (MIT) created a system in which, for the first time, many people could log onto the same computer using different dial-up connections and each person could store data in the computer. From this, people discovered many innovative ways to send messages between the different dial-up connections connected to the central computer.

In 1971, Ray Tomlinson developed a way to communicate between these computers by using the ‘@’ symbol, therefore leading email closer to the modern-day version.

According to the website How-to Geek, “email was, at that time, the equivalent of today’s text message. Over time, it changed and evolved like anything else; it has sender and receiver info, a subject line, a message body, and attachments, but on the whole, emails are pretty simple documents.”

Email works in a series of steps by using a domain, which is the portion of an email message after the ‘@’ symbol. For example, in the email address bob@cmu.edu, cmu.edu is the domain. The domain identifies the computer network the email is going to.

After a user presses “send” on the computer, the email actually gets sent by the computer to an outgoing mail server through the Simple Mail Transfer Protocol (SMTP). According to How-to Geek, “The SMTP server is like your local post office, which checks your postage and address and figures out where to send your mail.” However, the SMTP server cannot find an address by looking at the domain. It therefore contacts another server known as the Domain Name Server (DNS).

The DNS is like the internet’s yellow pages. It has the ability to convert a domain like cmu.edu to an IP address, which is a numerical address assigned to a device on a computer network, such as 128.2.42.10. The DNS also checks to see if the domain has any mail exchange servers on it, then sends all that information back to the SMTP server.

The SMTP server sends the message to the correct server identified by the DNS, called a Mail Transfer Agent (MTA). The MTA takes the information sent into it and decides exactly where to put the email.

After its long journey that takes place over a few seconds, the email finally reaches its destination. There are two primary conventions for receiving email: Post Office Protocol (POP) and Internet Message Access Protocol (IMAP). POP works similar to a post office: users can just connect to the internet, get all their email from the server, and then disconnect from the internet. It is very useful if one wants to take mail from different inboxes and put them all in the same place.

IMAP, however, allows you to store the email in a server and simply access it from different clients like your phone, iPod, and laptop. That way, if one reads a message on a laptop, it will still be marked as read when one accesses email through a phone. With the increasing popularity of web-based mail services and users with multiple devices, IMAP has largely replaced POP.

In summary, sending and receiving email is a little more complicated than what users see when they click “send” or open their inbox. The sent email goes to a SMTP server which then contacts a DNS. Then the email travels through the internet to a particular domain and its MTA server, from which it can go to a particular user’s account. The user can then fetch the email from his or her account through either POP or IMAP depending on his or her preference.

However, all of this happens behind the scenes; users are never informed of these events in the seemingly simple process of sending an email. Whether the message is connecting two distant family members, rekindling old friendships, or relaying important business information, many may find it difficult to deny the importance of email. Especially with today’s fast-paced society, the absence of email would bring textual communication to a screeching halt.