First Network Email (1971): Ray Tomlinson and the @ Sign

The first network email was sent in late 1971 by Ray Tomlinson, an engineer at the research firm Bolt Beranek and Newman (BBN) in Cambridge, Massachusetts. He sent a message from one computer to another across ARPANET, the US research network that grew into the internet, and chose the @ sign to separate a user’s name from the name of their computer. That small decision still shapes billions of email addresses today.

Background: messages on shared computers

In the 1960s most computers were large, expensive machines shared by many users through terminals, a system called time-sharing. Programmers soon wanted to leave notes for one another. From around 1965, MIT’s Compatible Time-Sharing System offered a MAIL command, and similar programs appeared on other systems.

These early programs had one limit: sender and recipient had to use the same computer. A message was simply written into a file that the other user would see when they logged in.

In 1969 the US Defense Department’s Advanced Research Projects Agency began linking university and research computers through ARPANET, which carried its first message in October that year. BBN had built the network’s packet-switching nodes and also ran its own computers on it.

What Tomlinson did

At BBN, Tomlinson worked on TENEX, an operating system for Digital Equipment Corporation PDP-10 computers. TENEX already had a local mail program called SNDMSG, and Tomlinson had been working on an experimental file-transfer program called CPYNET that could move files between computers on the network.

In late 1971 he combined the two ideas. He changed SNDMSG so that, instead of only adding a message to a mailbox file on the same machine, it could use CPYNET to append the message to a mailbox file on another computer. Tomlinson later said it was not an assignment; it simply seemed a neat idea.

He tested it between two PDP-10 machines that stood side by side in the same room at BBN but were connected only through ARPANET. The test messages, he recalled, were forgettable strings of characters. Once it worked, he sent a note to colleagues explaining how to use the new feature, so the first real use of network email was to announce network email.

The @ sign

Tomlinson needed a way to tell the program which computer a mailbox was on. He wanted a single character that would never appear in a person’s login name. He looked at the keyboard of his Model 33 Teletype terminal and chose @, which also read naturally as “at”.

The result was the user@host format: a name, the @ sign and the name of the machine. Early addresses were short, but the format scaled as the network grew and later gained domain names, giving addresses of the kind still used today.

How email spread

Email caught on quickly among ARPANET users. In 1972 Larry Roberts, who directed the network programme at ARPA, wrote a program for listing, reading, filing and replying to messages, making it far easier to handle a growing inbox.

By the mid-1970s surveys found that email accounted for a large share, by some estimates the majority, of traffic on ARPANET. That was a surprise: the network had been funded to let researchers share expensive computing power, not to carry personal messages.

Rules followed. Network standards documents in the 1970s defined headers such as “From”, “To” and “Subject”, and in 1982 the Simple Mail Transfer Protocol (SMTP) set out how mail servers should pass messages to one another. SMTP, in updated form, still carries most of the world’s email.

Myths and facts

Tomlinson is often called the inventor of email. That is only partly accurate: messaging within a single computer existed several years earlier. His contribution was sending mail between separate computers across a network, together with the user@host address format.

It is also sometimes said that the first email contained a famous phrase. In fact no record of its content survives, and Tomlinson himself said it was probably nothing more than test characters such as “QWERTYUIOP”.

Legacy

Tomlinson continued to work at BBN for most of his career. He was inducted into the Internet Hall of Fame in 2012 and received other honours, and he died in March 2016 at the age of 74.

Email became one of the first applications that made computer networks useful to ordinary people. It moved onto the wider internet in the 1980s and to the public in the 1990s, and it remains central to business and personal life, from early university systems to the inboxes on smartphones.

Timeline

• 1965: MIT’s Compatible Time-Sharing System offers a MAIL command for users of the same computer.
• 1969, 29 October: ARPANET carries its first message between UCLA and Stanford Research Institute.
• 1971, late: Ray Tomlinson sends the first email between two computers on ARPANET and adopts the @ sign.
• 1972: Larry Roberts writes a program for reading and managing email.
• 1982: The Simple Mail Transfer Protocol (SMTP) is published as a standard.
• 1983, 1 January: ARPANET switches to the TCP/IP protocols used by the internet.
• 2016, 5 March: Ray Tomlinson dies at the age of 74.

Why it matters

Tomlinson’s experiment turned a network built for sharing computers into a network for connecting people. The user@host address he devised in a few minutes became one of the most familiar conventions of the digital age.