How does the Email System Work

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 a company, are carried out through emails. This medium provides a quick as well as secured transmission of text, files, graphics, etc. E-mail 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 these emails are delivered, one might marvel at how the email system works and how the whole concept evolved. The history of global Internet e-mail service dates back to 1973, when the standards for encoding of messages were proposed. Emails sent in the early 1970s were very similar to ones which 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 Email Address

user@provider.com

In the address mentioned above, 'user' refers to the recipient's user name. Generally these user names are a single word representation of any convenient choice of name by a user. The naming conventions for different companies vary, however, 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 like com (commercial), gov (government), mil (military), edu (educational institution), org (non-profit organization), etc.

Working of the Email System

After composing an email, when a user clicks on the 'send' button, it actually takes a non-specific route, which varies from message to message. The email 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: The header field consists of the summary (subject) of the mail, its sender, receiver and other relevant information.
• Body: The body field consists of the text and attachments inside the mail and sometimes a signature block at the end. Both these fields (header and body) resemble those of a regular letter.

In case the email 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 the email to find the optimum path towards its ultimate destination. On reaching the recipient's network, the email 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 email 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 e-mail system consists of, is 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.