Electronic mail, sometimes called email, is a computer-based method of sending messages from one computer user to another. These messages usually consist of individual pieces of text which you can send to another computer user even if the other user is not logged in (i.e. using the computer) at-the-time you send your message. The message can then be read at a later time. This procedure is analogous to sending and receiving a letter.
Originally, email messages were restricted to simple text, but now many systems can handle more complicated formats, such as graphics and word-processed documents.
When mail is received on a computer system, it is usually stored in an electronic mailbox for the recipient to read later. Electronic mailboxes are usually special files on a computer that can be accessed using various commands. Each user normally has their individual mailbox.
It is straightforward to send electronic mail between users of different computer systems that are connected to major networks. Most major academic and research institutions and companies throughout the world can now be reached by electronic mail. In addition, a growing number of individuals can be contacted in this way.
All email systems have the ability to send, receive and discard mail. Most systems have facilities for storing mail that is to be kept rather than discarded. It is important to discard mail that does not need to be kept, as it uses storage space on disks. Mailboxes can soon accumulate a large number of mail messages making it difficult to read and process new mail, in addition to wasting disk space.
There is almost always a connection between the email system and the computer’s standard file system which allows mail to be read from files or written to files. This enables greater flexibility in how the mail system is used. For example, a mail message may be prepared in a normal file using a familiar text editor and then sent by the email system. Sections of other files may be included in the mail message as well.
Most systems have a reply facility, although some of these do not always work as expected. Care should be taken when using this facility in electronic mail, as replies do not always go back to the sender.
The recipient of mail may not always be an individual but could be a service such as a Helpdesk, Postmaster, a mailing list, or an automatic processing service.
Mailing lists are supported by many systems. These allow mail that is sent to the name of the list to be sent automatically to all addresses in that list. In this way, mail can be sent to one or more groups of users who share a common interest, e.g. members of a user group or research team, by sending a single message. A number of information services are also available through electronic mail whereby the mail is processed and answered by an automatic process on the remote system.
Email is much older than ARPANet or the Internet. It was never invented; it evolved from very simple beginnings.
The early email was just a small advance on what we know these days as a file directory — it just put a message in another user’s directory in a spot where they could see it when they logged in. Simple as that. Just like leaving a note on someone’s desk.
Probably the first email system of this type was MAILBOX, used at Massachusetts Institute of Technology froth 1965. Another early program to send messages on the same computer was called SNDMSG.
Some of the mainframe computers of this era might have had up to one hundred users — often they used what is called ‘dumb terminals’ to access the mainframe from their work desks. Dumb terminals just connected to the mainframe — they had no storage or memory of their own, they did all their wor4 on the remote mainframe computer.
Before internetworking began, therefore, the email could only be used to send messages to various users of the same computer. Once computers began to talk to each other over networks, however, the problem became a little more complex. We needed to be able to put a message in an envelope and address it. To do this, we needed the means to indicate to whom letters should go that the electronic pasties understood — just like the postal system, we needed a way to indicate an address.
This is why Ray Tomlinson is credited with inventing email in 1972. Like many of the Internet inventors, Tomlinson worked for Bolt Beranek and Newman as an ARPANET contractor. He picked the @ symbol from the computer keyboard to denote sending messages from one computer to another. So then, for anyone using Internet standards, it was simply a matter of nominating [email protected]
Despite what the world wide web offers, email remains the most important application of the Internet and the most widely used facility it has. Now more than 1000 million people internationally use email.
By 1974 there were hundreds of military users of email because ARPANet eventually encouraged it. Email became the savior of ARPANet and caused a radical shift in Arpa’s purpose.
Things developed rapidly from there. Larry Roberts invented some email folders for his boss so he could sort his mail, a big advance. In 1975 John Vital developed some software to organize email. By 1976 email had really taken off, and commercial packages began, to appear. Within a couple of years, 75% of all ARPANet traffic was email.
Email took us from ARPANet to the Internet. Here was something that ordinary people all over the world wanted to use. As Ray Tomlinson observed some years later about email, “any single development is stepping on the heels of the previous one and is so closely followed by the next that most advances are obscured. I think that few individuals will be remembered.” That’s true—to catalog all the developments would be a huge task.
One of the first new developments, when personal computers came on the scene, was ‘offline readers’. Offline readers allowed email users to store their email on their own personal computers, and then read it and prepare replies without actually being connected to the network—sort of like. Microsoft Outlook can do today.
This was particularly useful in parts of the world where telephone costs to the nearest email system were expensive. With connection charges of many dollars a minute, it mattered to be able to prepare a reply without being connected to a telephone, and then get on the network to send it. It was also useful because the ‘offline’ mode allowed for more friendly interfaces. Being connected directly to the host email system in this era of very few standards often resulted in delete keys and backspace keys not working, no capacity for text to ‘wrap-around’ on the screen of the user’s computer, and other such annoyances. Offline readers helped a lot.
The first important email standard was called SMTP, or simple message transfer protocol. SMTP was very simple and is still in use. SMTP was a fairly naive protocol and made no attempt to find out whether the person claiming to send a message was the person they purported to be. The forgery was (and still is) very easy in email addresses. These basic flaws in the protocol were later to be exploited by viruses and worms, and by security frauds and spammers forging identities. Some of these problems are still being addressed.
When Internet standards for email began to mature the POP (Post Office Protocol) servers began to appear as a standard — before that each server was a little different. POP was an important standard to allow users to develop mail systems that would work with each other.
These were the days of per-minute charges for email for individual dialup users. For most people on the Internet in those days, email and email discussion groups were the main uses. There were many hundreds of these on a wide variety of topics, and as a body of newsgroups, they became known as USENET.
With the World Wide Web, email started to be made available with friendly web interfaces by providers such as Yahoo, Hotmail, Gmail, Rediffmail, etc. Usually, this was without charge. Now that email was affordable, everyone wanted at least one email address, and the medium was adopted by not just a hundred million, but thousands of millions of people.