In 1967, he joined the technology company of Bolt, Beranek and Newman (BBN; now
Raytheon BBN), where he helped develop the
TENEX operating system including the
ARPANET Network Control Program, implementations of
Telnet, and implementations on the self-replicating programs
Creeper and Reaper. Tomlinson also developed CPYNET, a file transfer program designed to transmit files between computers connected to the ARPANET. In 1971, he was asked to adapt an existing program called
SNDMSG—which allowed users to leave messages for others on the same
time-sharing computer—so that it could run on TENEX. He incorporated
source code from CPYNET into SNDMSG, enabling users to send messages to others on
different computers over the network. This innovation marked the creation of the first networked email system. The first email Tomlinson sent was a test message between two computers placed side by side. The content of the message was not preserved, and Tomlinson later described it as insignificant, likely consisting of a random string such as "
QWERTYUIOP." This is often misquoted as "The first e-mail was QWERTYUIOP." He later stated, "The test messages were entirely forgettable and I have, therefore, forgotten them." To distinguish destination addresses from local usernames, Tomlinson selected the
@ symbol to indicate the recipient's location (user@host), a format that remains standard in
email addressing. The symbol was chosen because it was not used in usernames or in TENEX programming, and it intuitively conveyed the intended meaning. The @ sign, which was relatively obscure at the time, was added to the
Museum of Modern Art's architecture and design collection in 2010, credited to Tomlinson and described as a "defining symbol of the computer age." Initially, the email messaging system was not considered significant. Its development was not directed by his employer, and Tomlinson pursued the idea independently, stating that it "seemed like a neat idea." Despite its informal origins, the system quickly gained popularity within the ARPANET research community and became one of the network's most enduring applications. Tomlinson said he preferred "email" over "e-mail," joking in a 2010 interview that "I'm simply trying to conserve the world's supply of hyphens" and that "the term has been in use long enough to drop the hyphen." ==Later life and death==