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Email: Working of Email

Table of Contents:

  1. Email: Working of Email
  2. Email Working
  3. Email Protocols

Written By: 

Anshul Thakur

 

Since the dawn of time, communication has played a pivotal role in advance of every great civilization. It has been a constant endeavor to convey things in a fast and secure manner in the absence of which, great empires have just succumbed to crisis. There is an old saying that highlights the feat that a little miscommunication achieved, ‘For the want of a nail, a horseshoe was lost. For the want of a horseshoe, the steed was lost. For the want of a steed, the message was not delivered. For the want of that undelivered message, the war was lost.’ The means to transport and deliver messages have evolved ever since. From barefoot messengers, horse riders and pigeons to organized postal services carrying letters in parchment form and then, to telegraph and modern electronic mail systems delivering messages over streams of electrons in a wire or over wireless electromagnetic links, the entire concept of sending mails has gone a thorough makeover. Of all the modern means of communication, electronic mail is one such means that still encapsulates the core ideology of writing, and adapting it to modern times, ensuring accurate and timely delivery.
What is E-Mail
History
Message exchange has existed in some form or the other since the time of timeshared computers. Compatible Time-Sharing System (CTSS) started off in MIT in 1961 where multiple users could log on using remote dial-up terminals and store files online. To share messages, users made files with the names of the person being addressed to and put it up on the shared folder. In 1971, Ray Tomlinson developed the first ARPANET email application by adding a program CPYNET on top of the local email programs SNDMSG and READMAIL for the TENEX OS. This piece of code was capable of copying files over the network and used the ‘@’ symbol to combine user and host names as a part of its addressing system. Though it was command line driven, it set up the basic model that still is the framework of email systems. Until the Simple Mail Transport Protocol (SMTP) was developed in 1980’s, the commands like MAIL and MLFL were added to the FTP program to provide network transport functionalities to emails on ARPANET. Among other features, SMTP allowed the sending of a single message to more than one addressee on a domain.
 
Lawrence Roberts, wrote a program named RD for TENEX which was later improved into NRD by Barry Wessler to sort email headers by date and subject allowing users to sort their mails and various other features. Marty Yonke later recoded SNDMSG and NRD into an independent program WRD (later renamed to BANANARD) which became the first program to integrate reading and sending mails on a single application. Features like forwarding, configurable interfaces and Answer command (which made the mails look more like threaded conversations rather than independent mails) were added upon BANANARD by John Vittal and the program was named MSG. This could be considered to be the first modern email program. In 1975, DARPA initiated a program to develop mailing capabilities for UNIX environment as a result of which, Mail Handler (MH) was developed, which became the standard email application for Unix. Standardization followed in 1977 in the form of RFC 733 specifications which was later revised to RFC 822. The ability to deliver mail over dial up connections which weren’t connected to ARPANET was developed at University of Delaware by the name of Multi-purpose Memo Distribution Facility (MMDF).
 
Various other people like Doug Kingston enhanced it like developing the TCP/IP layer and integrated into other networks like CSNET. Eric Allman later developed ’delivermail’ which integrated multiple email transport services, creating a sort of switch and became the most popular SMTP server used on internet. The first commercial email service was launched in 1988 through CNRI for experimental use. By 1993 network providers like AOL and Delphi had started to connect their email systems to internet, beginning the era of adoption of internet email as a global standard. The term ‘email’ was copyrighted by V.A. Shiva Ayyadurai on 30th August 1982.
 
Structure of E-Mail
Electronic mail or simply email is a method of sending and receiving messages in a digital form between users. Primarily it is a simple text message addressed to another user who is called the recipient. With the addition of features like attachments along with email messages, the size of the message might have increased, but they still are text messages.
 
An email message contains 3 components: envelope, header and a message body. Envelope is a part that the user of email would never see. It is an internal process used in routing the email to the appropriate destination. Body is the part of the message that contains the useful data meant for the recipient. The header consists of the control information which includes the sender’s address and the destination address in its minimalistic form. Further it may contain the subject header information and the time stamp of various mail transfer agents. Some of these values may be taken directly from the envelope information. A typical header may look like one in the figure below:
 
Example of Email Header, Structure of Email
There is an additional feature of adding a signature block to an email. This can be the user’s name, title or legal notice that might be added to all emails of that person. Typing the same thing in each mail can get tedious, thus this signature which is automatically appended at the end of the body of the email may be used instead. A signature may be created following certain rules called netiquette (network etiquette).
 

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