Functions of Email System
Functions of Email System
Email, also sometimes written as e-mail, is simply the shortened form of electronic mail, a protocol for receiving, sending, and storing electronic messages. Email has gained popularity with the spread of the Internet. In many cases, email has become the preferred method of communication. As email has come into picture, the task of sending and receiving messages has become very easy. It also eliminates time delays and the other problem which you can face if the message will be delivered physically. It is used frequently in our day to day life now as it is very simple to use. Electronic mail means to send or receive messages electronically. It means electronic mail is a method of exchanging digital messages from an author to one or more recipients. Email was invented by Ray Tomlinson, a computer engineer in late 1971. The first message was sent between the two computers that were sitting beside each other. The first message was ‘QWERTYUIOP”. The network used for transferring the message was ARPANET. Ray Tomlinson used @ symbol to combine the user and the host names user@host like abc@xyz.com. This is usually called address of the person to whom you want to send the message. Tomlinson’s idea was to identify the name of the user and the computer at which he or she was located. As a result, the basic formula for addressing an email was username@usercomputer. This standard has not changed much over the years, other than the user computer now commonly being replaced by the name of an email provider. In some cases, this is the same as the user’s Internet service provider. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the same time, in common with instant messaging. Today’s email systems are based on a store-and-forward model. Email servers accept, forward, deliver and store messages. Neither the users nor their computers are required to be online simultaneously; they need connect only briefly, typically to an email server, for as long as it takes to send or receive messages. Email, in today’s age has become one of the most widely used internet application. You can send messaged to the other people who are connected with each other through a network. Most of the people in business, government and education prefer using email in comparison to conventional mail which is also known as snail mail for communicating with their colleagues. Email has contributed a lot to the growth of internet as it has brought close together families and friends that are spread all around the world. Below figure shows hoe email works. Email passes from one compute, known as a mail server, to another as it travels over the internet. Once it arrives at the destination mail server, it’s stored in an electronic mailbox until the receipt retrieves it. The whole process can take place in seconds even it sending around the world. To receive an email you need an account on a mail server like yahoo, gmail etc. 
An email message consists of three components, the message envelope, the message header, and the message body. The message header contains control information, including, minimally, an originator’s email address and one or more recipient addresses. Usually descriptive information is also added, such as a subject header field and a message submission date/time stamp. Originally a text-only (7-bit ASCII and others) communications medium, email was extended to carry multi-media content attachment (e.g. attaching files, images etc.) The protocols which are used to deal with email are SMTP (Simple Mail Transfer Protocol), POP (Post Office Protocol) and IMAP (Internet Message Access Protocol). SMTP protocol is used to transfer the messages over a network and also gives an indication of incoming messages. POP protocol is used to enable the users to move their emails from mail server to their computers. It works in offline access mode. It is just like a real post office, which collects all the pending mails from the mail server to the user’s own computer. IMAP protocol enables a user to manipulate email messages in the server without downloading them to the user’s own computer. You can view just the heading and the sender of the email and then you can decide what you want to do with the message. Whether you want to download it or want to delete it. Email service should be used with some precautions. Your account can be hacked or if you are transferring some critical information, it can be stolen while transferring. So use email service carefully. Email client is an application which is used to handle mail system. The functions of Email client are mention below: · Shows you a list of all of the messages in your mailbox by displaying the message headers. The header shows you who sent the mail, the subject of the mail and may also show the time and date of the message and the message size.
· Lets you select a message header and read the body of the e-mail message.
· Let’s you create new messages and send them. You type in the e-mail address of the recipient and the subject for the message, and then type the body of the message.
· Lets you add attachments to messages you send and save the attachments from messages you receive.
There are two programs or application Mail User Agent (UA) and Mail Transfer Agent (MTA) are available in mail system for composing, reading, replying, forwarding messages, handling mailboxes and transferring mail from server to server & source to destination. UA and MTA are described in following section. 
