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How Does the Email System Work?

How Does the Email System Work?

Email services are used by millions of people worldwide for the transmission of text, data, etc. Read on to know how this system works.
Swapnil Srivastava
Email accounts are an indispensable part of our day-to-day lives, both at the organizational and individual level. Most of the formal business communications within the company are carried out through them. This medium provides a quick as well as secured transmission of text, files, graphics, etc. Email systems are primarily based on a store-and-forward model, which enables the computer server to accept, forward, deliver, and store messages. Looking at the speed with which they are delivered, one might marvel at how this system works, and how the whole concept evolved. The history of the global Internet e-mail service dates back to 1973, when the standards for encoding of messages were proposed. Those sent in the early 1970s were very similar to ones that constitute the Internet traffic today. Initially, the network-based email transmission used the File Transfer Protocol (FTP), but today, it is governed by the Simple Mail Transfer Protocol (SMTP).

A Typical Example

In this address, "user" refers to the recipient's user name. Generally, these user names are a single word representation of any convenient choice of the name by the user. The naming conventions for different companies vary, but the basics remain the same. The domain name of the organization is reflected by the "provider" part of the address, and it tells about the location of the user's mailbox. The last part "com" refers to the type of organization providing the mail server. There are various organizations such as com (commercial), gov (government), mil (military), edu (educational institution), org (non-profit organization), etc.

Working of This System

After composing an email, when the user clicks on the "send" button, it takes a non-specific route, which varies from message to message. It is first wrapped up in a digital envelop, which contains the recipient's address, sender's address, and various other things. The SMTP (Simple Mail Transport Protocol) server is used for the purpose of handling the outgoing mails. An email is basically divided into two parts:
  • Header: This field consists of the summary (subject) of the mail, its sender, receiver, and other relevant information.
  • Body: It consists of the text and attachments inside the mail, and sometimes, a signature block at the end. Both these fields resemble the ones of a regular letter.
In case it has to be sent to an address of the same domain, the SMTP server would simply hand the message to the POP3 server of the same, using the delivery agent. Otherwise, it communicates with the DNS (Domain Name Server) in order to find the IP address of the destination host. An email takes a number of stops before reaching its destination, and at each stop, it is stored temporarily. These intermediate halts also allow it to find the optimum path towards its ultimate destination. On reaching the recipient's network, it is routed to the user's inbox, by the email computer. Once it gets stored in the inbox, the recipient can easily see it by logging into his account and opening the mail.

The whole process of its transmission might seem like a lengthy task; however, as the messages travel at nearly the speed of light, the longest hop between networks takes less than the blinking of an eye. Almost all the real email systems consist of two different servers, namely the SMTP server, which handles outgoing mails, and the POP3 (Post Office Protocol) server or an IMAP server, for handling the incoming mails.