Electronic Mail

Electronic mail (email) was created to allow two individuals to communicate using computers. In early days, the email technology allowed one person to type a message and then send it to another person over the Internet. It was like posting a letter, except that the communication was electronic, instead of on paper. These days, email facility allows many features such as:

• Composing and sending/receiving a message,
• Storing/forwarding/deleting/replying to a message with normally expected facilities, such as carbon copy (CC), blind carbon copy (BCC) etc.,
• Sending a single message to more than one person,
• Sending text, voice, graphics and video,
• Sending a message that interacts with other computer programs The best features of email are:

(a) The speed of email is almost equal to that of telephonic conversations.

(b) The recording of the email messages in some form is like the postal system (which is even better than the telephone system). That is, emails are recorded in writing.

Thus, email combines the best of the features of the telephone system and the postal system, and is still very cheap. From the view point of users, email performs the following five functions:

(a) Composition: The email system can provide features in addition to the basic text editor features such as automatic insertion of the receiver's email address when replying to a message.

(b) Transfer: The email system takes upon itself the responsibility of moving the message from the sender to the receiver by establishing connections between the two computers and transferring the message using TCP/IP.

(c) Reporting: The sender needs to know whether the email message was successfully delivered to the receiver, or it did not reach the receiver for whatever reason. The email system performs this reporting task as well.

(d) Displaying: The email system displays the incoming messages in a special pop up window, or informs the user in some way that an email message has arrived. The user can then open that message on the screen.

(e) Disposition: This includes features such as forwarding, archiving and deleting messages that have been dealt with. The user can decide what to do with such an email message, and instruct the email system accordingly.

There is a tremendous similarity between the postal system and the email system. When we write a letter to someone, we put it in an envelope, write the intended recipient's name and the postal address on the envelope and drop it in a post box. The letter then goes via one or more interfaces, such as inter state or inter country postal services. It also passes through various nodes, where sorting and forwarding of letters take place. Remember, the pin code comes handy for this! Finally, it arrives in the personal mailbox of the recipient. (Here, we imagine that each resident has a post mailbox near his house. We may also assume that the person checks the mailbox for any letters twice a day). Here, a person from New York wants to send a letter to her friend in Brighton (England).

Email does not work very differently than this. The major difference between postal mail and email is the interface. Whereas postal system has humans coordinating most of the communication (say New York to London, London to Brighton) in terms of moving the letter forward, in the case of emails, it is all handled by one or more intermediate routers, as studied earlier. Email uses TCP/IP as the underlying protocol. This means that when a person X writes a message to Y, it is broken down into packets according to the TCP/IP format, routed through various routers of the Internet and reassembled as the complete email message at the destination before it is presented to Y for reading.

Interestingly, email first started with people sending files to each other. The convention followed was that when it was required to send an electronic message, the person would send a file instead, with the desired recipient's name written in the first line of the file. However, people soon discovered the following problems with this approach:

(a) There was no provision for creating a message containing text, audio and video.

(b) The sender did not receive any acknowledgement from the receiver, and therefore, did not know if the message had indeed reached the receiver.

(c) Sending the same message to a group of people was difficult with this approach. Examples of such situations are memos or meeting invitations sent to many people.

(d) The user interface was poor. The user had to first invoke an editor, type the message into a file, close the editor, invoke the file transfer program, send the file, and close the file transfer program.

(e) The messages did not have a pre defined structure, making viewing or editing cumbersome.

Considering these problems, it was felt that a separate application was needed to handle electronic messaging. That is when email was born!

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