Ray Tomlinson

Abstract

Ray Tomlinson (1941–2016) put the @ sign in email addresses. In late 1971, working at Bolt Beranek and Newman on a contract that did not ask for it, he spliced a file-transfer program into a local messaging program and sent the first electronic mail between two computers on the ARPANET. He needed a character to separate the user from the machine, picked @ because nobody’s name contained one, and thereby standardised the address format for every network on earth. He told nobody outside his group at first, describing it later as something not to mention because it was not what they were supposed to be working on. He spent the next forty-five years at the same company, wrote the first program that copied itself across a network and the first program that hunted it down, and consistently declined to describe any of it as important.

RPI, MIT, BBN

Tomlinson was born on April 23, 1941 in Amsterdam, New York, and grew up in the small town of Vail Mills. He took a bachelor’s degree in electrical engineering at Rensselaer Polytechnic Institute in 1963 on a co-op programme with IBM, then went to MIT, where he worked in the Speech Communication Group on an analog-digital hybrid speech synthesiser and took his master’s in 1965.

He joined Bolt Beranek and Newman in Cambridge, Massachusetts in 1967. BBN was the contractor that had won the job of building the ARPANET’s Interface Message Processors, the packet switches that made the network work, so Tomlinson landed inside the group that was assembling the network itself. See ARPANET: Building the Network and Larry Roberts and ARPANET.

His assigned work was the TENEX operating system, BBN’s time-sharing system for the DEC PDP-10, and he wrote its implementation of the ARPANET Network Control Program and its file transfer program, CPYNET. TENEX was the most popular customer-written system for the PDP-10, and it ran on 28 ARPANET hosts, which is why what Tomlinson wrote next travelled as far as it did.

The Side Project

Time-sharing systems already had mail. TENEX had SNDMSG, which let one user of a machine append a message to another user’s mailbox file on the same machine. It was useful and entirely local.

In late 1971 Tomlinson noticed that he had both halves of something. SNDMSG knew how to append to a mailbox. CPYNET knew how to move bytes to another host over the ARPANET. He modified SNDMSG so that a destination containing a host name would hand the message to CPYNET code, which would append it to a mailbox on the remote machine. BBN had two PDP-10s on the network, sitting next to each other in the same room; the first messages went from one to the other, taking the long way through the ARPANET.

The separator problem was the interesting design decision. The address needed one character that could never appear in a user name. Tomlinson looked at what was on the Model 33 Teletype keyboard, found @ doing nothing, and noticed it already read as the English word “at”. user@host needed no explanation, and nobody has proposed a replacement in fifty-five years. The Museum of Modern Art acquired the @ sign for its architecture and design collection in 2010, crediting the acquisition to Tomlinson’s use of it.

Myth: the first email said “QWERTYUIOP”

Tomlinson never said this. Asked repeatedly, his answer was that the test messages were entirely forgettable and that he had therefore forgotten them; his best guess was that one may have been something like QWERTYUIOP, and journalists hardened the guess into a quotation. He also called it “the first email not worth reading”. No record of the content survives. See Myths and Misconceptions.

He mentioned it to his colleague Jerry Burchfiel with the remark, often quoted since, not to tell anyone, because this was not what they were supposed to be working on.

The detailed account of that week is in Fun Fact: The First Email and Fun Fact: The @ Symbol; what happened to email afterwards is in Email: The Killer App.

What It Did to the Network

The ARPANET had been funded to let researchers share expensive computers. Within two years of Tomlinson’s modification, an ARPA study found electronic mail accounting for around three quarters of all traffic on it. The network built for remote login and file transfer had become a communications medium, and its own designers were the ones who converted it.

Tomlinson’s format spread with the software. Because TENEX ran on most of the early ARPANET, his SNDMSG went everywhere, and user@host was already universal by the time anyone standardised it. The subsequent mail RFCs, and eventually SMTP in 1982, wrote down what Tomlinson had already made conventional.

Creeper and Reaper

Tomlinson also has a claim on the origins of computer viruses and antivirus software, which he did not seek either.

Creeper, written by Bob Thomas at BBN around 1971, was an experimental program that moved itself between TENEX machines on the ARPANET, printing “I’M THE CREEPER: CATCH ME IF YOU CAN”. Tomlinson rewrote it so that instead of merely moving, it copied itself to the next machine while remaining on the current one, which made it the first self-replicating program to spread over a network. He then wrote Reaper, which travelled the same way and deleted Creeper instances it found. Neither was malicious; the point was to explore whether a program could migrate along with its running state. See Fun Fact: Reaper, the First Antivirus.

Staying Put

Tomlinson worked at BBN for the rest of his career, through its acquisitions by GTE, Verizon, and Raytheon, on network protocols and speech and internetworking projects that were mostly not email. He gave few interviews and was uncomfortable with the ones he gave, deflecting significance every time. Asked how he felt about being the father of email, his standard reply was that he had been solving a small problem with the tools in front of him.

He received the IEEE Internet Award in 2004 (with Dave Crocker), the Prince of Asturias Award for Technical and Scientific Research in 2009 (shared with Martin Cooper, who made the first handheld mobile phone call), the Webby lifetime achievement award, and induction into the Internet Hall of Fame in 2012. Asteroid 10108 is named Tomlinson.

He died of a heart attack at his home in Lincoln, Massachusetts on March 5, 2016, aged 74. He kept miniature sheep on the property.