E-mail Inventor who popularized @ symbol

Ray Tomlinson, E-mail inventor who popularized @ symbol

Ray Tomlinson, E-mail inventor who popularized @ symbol

Electronic mail (email or e-mail) is a method of exchanging messages (“mail”) between people using electronic devices. Email entered limited use in the 1960s, but users could only send to users of the same computer, and some early email systems required the author and the recipient to both be online simultaneously, similar to instant messaging. Ray Tomlinson is credited as the inventor of email; in 1971, he developed the first system able to send mail between users on different hosts across the ARPANET, using the @ sign to link the user name with a destination server. By the mid-1970s, this was the form recognized as email.

Email operates across computer networks, primarily the Internet. 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 to connect, typically to a mail server or a webmail interface to send or receive messages or download it.

Originally an ASCII text-only communications medium, Internet email was extended by Multipurpose Internet Mail Extensions (MIME) to carry text in other character sets and multimedia content attachments. International email, with internationalized email addresses using UTF-8, is standardized but not widely adopted.

The history of modern Internet email services reaches back to the early ARPANET, with standards for encoding email messages published as early as 1973 (RFC 561). An email message sent in the early 1970s is similar to a basic email sent today.

Tomlinson was born in Amsterdam, New York in 1941, and he earned a master’s degree from the Massachusetts Institute of Technology. In 1967, he joined Bolt Beranek and Newman (BBN), a company that played a key role in the development of the ARPANET, a precursor to the modern Internet.

In 1971, according to the Internet Hall of Fame, he wrote the first ARPANET mail client, combining the existing SNDMSG and CPYNET programs. Tomlinson himself came up with the idea of using the @ symbol as a way to separate local e-mails from those that could be sent to external networks through the user@host syntax.

As he wrote on his own website in the early 1990s:

“I was making improvements to the local inter-user mail program called SNDMSG. Single-computer electronic mail had existed since at least the early 1960’s and SNDMSG was an example of that. SNDMSG allowed a user to compose, address, and send a message to other users’ mailboxes.

A mailbox was simply a file with a particular name. It’s only special property was its protection which only allowed other users to append to the file. That is, they could write more material onto the end of the mailbox, but they couldn’t read or overwrite what was already there. The idea occurred to me that CPYNET could append material to a mailbox file just as readily as SNDMSG could. SNDMSG could easily incorporate the code from CPYNET and direct messages through a network connection to remote mailboxes in addition to appending messages to local mailbox files.

The missing piece was that the experimental CPYNET protocol had no provision for appending to a file; it could just send and receive files. Adding the missing piece was a no-brainer—just a minor addition to the protocol. I don’t recall the protocol details, but appending to a file was the same as writing to a file except for the mode in which the file was opened.

Next, the CPYNET code was incorporated into SNDMSG. It remained to provide a way to distinguish local mail from network mail. I chose to append an at sign and the host name to the user’s (login) name. I am frequently asked why I chose the at sign, but the at sign just makes sense. The purpose of the at sign (in English) was to indicate a unit price (for example, 10 items @ $1.95). I used the at sign to indicate that the user was “at” some other host rather than being local.“