In late 1971, a computer engineer named Raymond Tomlinson was working at Bolt, Beranek and Newman in Cambridge, Massachusetts, on two separate programs for the ARPANET — the experimental computer network that would eventually become the internet. One program, SNDMSG, allowed users on the same computer to leave messages for each other in local mailboxes. The other, CPYNET, transferred files between different computers on the network. Tomlinson had the obvious idea: combine them. Use the file transfer protocol to deliver a message not just to a local mailbox but to a mailbox on any machine connected to the ARPANET. Network email, in other words. The concept was straightforward once stated, but no one had stated it.
The technical problem was equally straightforward. To deliver a message to a specific user on a specific computer, the system needed a way to write the destination address that contained both pieces of information: who the recipient was, and what machine they were on. The address needed a separator between the two — a single character that the email software could parse, that wouldn’t be confused with any part of a username, and that wouldn’t conflict with the existing commands of the TENEX operating system the BBN team was using. Tomlinson looked at the Model 33 Teletype keyboard in front of him and considered what was available.
The character he chose
The “@” symbol had been sitting on typewriter and teletype keyboards since the late 19th century, where it had been included largely as a courtesy to bookkeepers and grocers. The symbol’s original meaning was commercial — “at the rate of,” as in “10 widgets @ $5” — and it had been used in the same sense in European commerce for centuries before that. By 1971 it was, in the words of a CBS News retrospective, “used almost exclusively by grocers and accountants.” It had no role in programming languages of the era, no use in any operating system command, and no occurrence at all in human names. Tomlinson scanned for a character that met those criteria, and the @ symbol was the one that did.
He explained his reasoning in a 2012 interview with Smithsonian magazine, quoted in his subsequent obituary in the Boston Globe: “I was mostly looking for a symbol that wasn’t used much. And there weren’t a lot of options — an exclamation point or a comma. I could have used an equal sign, but that wouldn’t have made much sense.” The @ symbol had a second virtue beyond its rarity. It could be read aloud as “at,” which meant the email address format produced a natural English phrase: user-at-host. Tomlinson later told an interviewer that the @ was “the only preposition on the keyboard,” and the choice had been partly a matter of grammatical fit.
The first network email was sent shortly after this decision, between two PDP-10 computers sitting in the same room at BBN, perhaps three metres apart, connected through the ARPANET. According to NPR’s memoriam interview with Tomlinson, the messages he sent during the testing phase were typically gibberish: random strings of characters, occasional phrases from the Gettysburg Address, or top-row keystrokes like “QWERTYUIOP.” When asked to recall the content of the very first email, Tomlinson said he could not. “The first email is completely forgettable,” he told NPR. “And, therefore, forgotten.”
How the choice propagated
Once the email system was working, Tomlinson used it to send the first email that was not a test: a message to his BBN colleagues explaining how the network email system worked and how to use it. The instructions included the new address format with the @ symbol. The colleagues adopted the system quickly. The early ARPANET community, then numbering perhaps a few hundred researchers across two dozen institutions, had a culture of trying interesting tools as soon as they appeared. Within a few weeks, network email was a regular feature of ARPANET life. Within a few years, it was the most-used application on the network.
The @ symbol travelled with the format wherever email went. When the ARPANET became the internet, the addressing convention came along unchanged. When the consumer internet emerged in the 1990s, services like Hotmail and Yahoo Mail built their offerings around the same syntax. When mobile email and webmail and corporate enterprise systems followed, none of them changed the basic structure. Every email address on Earth — and according to a recent industry estimate, there are now more than 5.6 billion active email accounts — uses the same format Tomlinson chose in 1971, with the same @ symbol separating user from host. The choice has been remarkably durable for a piece of software design that was, by Tomlinson’s own account, made in a few minutes on a Tuesday afternoon by an engineer who was “just fooling around.”
The man, briefly
Tomlinson did not anticipate that his choice would end up in the working vocabulary of the entire human population. According to the MIT Lemelson programme’s biographical entry on Tomlinson, he was born in Amsterdam, New York, on 23 April 1941 — a date now observed informally as “Email Day” in his honour. He studied electrical engineering at Rensselaer Polytechnic Institute, completing his bachelor’s degree in 1963, and earned his master’s at MIT in 1967. He joined BBN that same year as a principal engineer and stayed with the company for the rest of his career, even after it was acquired by Raytheon. The email system was one project among many. He continued to do quiet, technically excellent work on networking software for decades afterward. He raised miniature sheep at his home in Lincoln, Massachusetts. He gave occasional interviews when asked, but generally did not promote himself.
He was inducted into the Internet Hall of Fame in 2012. The Museum of Modern Art added the @ symbol to its design collection in 2010, with formal credit to Tomlinson for its modern usage. He continued working at Raytheon until his death from a heart attack on 5 March 2016, at the age of 74. He was widely described by colleagues as patient, generous with his time, and modest about his contributions. Asked years later whether he had understood what he was doing when he sent that first email, he gave a characteristic answer: “Yeah, I knew exactly what I was doing. I just had no notion whatsoever about what the ultimate impact would be.”
The @ symbol was, before Tomlinson, a piece of typographic furniture that almost no one used. It now appears in the contact list of every smartphone on Earth, in the network address of every email server, in every login screen of every corporate intranet, and in the casual signature of every public figure’s social media account. A character that grocers used to mark unit prices became the connective tissue of the world’s most widespread communication system, because one engineer in 1971 needed something to put between a username and a hostname, and the @ key happened to be the most obvious choice on his particular keyboard.
