Ray Tomlinson and the @ Sign: How Email Was Invented in 1971
In 1971 engineer Ray Tomlinson sent a message between two computers and chose the @ symbol for addresses. The history of email, from ARPANET to your inbox.
Email is older than the web, older than the commercial internet and older than most of the software that we now use to read it. It was created in 1971 by Ray Tomlinson, an engineer at the Cambridge, Massachusetts company Bolt, Beranek and Newman (BBN), the same firm that built the hardware for ARPANET.
Messages before networks
Electronic mail did not begin with the network. Time-sharing computers of the 1960s let many users share one large machine, and some of those systems let users leave messages for each other in files. Mail like this stayed on a single computer. If you wanted to write to someone on another machine, you needed another approach.
What Tomlinson did
Tomlinson was working on the TENEX operating system, which ran on DEC PDP-10 computers at BBN and at other ARPANET sites. TENEX already had a local program called SNDMSG for leaving messages in other users' mailboxes, and he was also working on an experimental file-transfer program for the network called CPYNET.
He combined the ideas. By adapting SNDMSG so that it could use the file-transfer capability to append a message to a mailbox file on a different computer, he made it possible to send mail from one host to another across ARPANET. His first test messages were sent between two machines in the same room. Tomlinson later said that the content of those tests was unmemorable, something like random keystrokes.
Why the @ sign
A message across a network needs two pieces of information: who the recipient is and which computer they are on. Tomlinson needed a character to separate the user name from the host name. He chose the @ symbol, which is read "at". It was already on the keyboard of the Teletype terminals he used, it was rarely used in names, and it made sense: user at host.
The result, user@host, is the format we still use. Today the part after the @ is a domain name, but the principle is identical.
Email spreads on ARPANET
Email caught on rapidly. Within a few years, studies of ARPANET traffic found that it accounted for a large share of the network's use. Several developments shaped how people used it:
- Programs for reading and sorting mail appeared, and in the early 1970s Larry Roberts wrote RD, an early mail-management program that could list, read, file and delete messages; later programs added replying and forwarding.
- Standards for headers (the From, To and Subject lines) were written down in the RFC series.
- Mailing lists let a single message reach a whole group.
The original ARPANET mail practice was formalised later as the Simple Mail Transfer Protocol (SMTP), published as RFC 821 in 1982 and updated several times since. SMTP is still the protocol that servers use to hand mail to each other.
Email as an unplanned success
ARPANET had been justified as a way to share computing resources. Email was a side effect that turned out to be more used than the intended purpose. The lesson is one of the most repeated in technology: people adopt tools that let them communicate with each other.
The problems that came with it
Because SMTP was designed in a small, trusting community, it did not verify who a message came from. Anybody could write any address in the From line. This design choice allowed spam to flourish once the network opened to the public, and it explains why we now have add-on systems for checking mail:
| Technology | What it does |
|---|---|
| SPF | Lists which servers may send mail for a domain |
| DKIM | Adds a cryptographic signature to outgoing messages |
| DMARC | Tells receivers what to do with mail that fails SPF or DKIM |
These standards were added decades after SMTP in order to fix a problem the original authors never expected.
Tomlinson's legacy
Tomlinson was inducted into the Internet Hall of Fame and died in 2016. He often downplayed his invention, describing it as a quick hack that seemed useful. There is no single date for the very first network email that all sources agree on, but 1971 is the year generally given.
From ARPANET mail to the inbox of today
The history after Tomlinson is a story of gradual additions rather than replacement. Personal computers brought desktop mail programs in the 1980s. Protocols for downloading mail to those programs, POP and later IMAP, were developed so that users did not have to log in to the server itself. Commercial services such as CompuServe and later web-based mail made email available to people who had never used a network before. Webmail arrived in the mid-1990s and changed the idea of where a mailbox lives.
Under all of that, the structure remains the same: your mail client submits a message to an SMTP server, the server looks up the recipient domain's MX record in DNS and delivers the message to the server named there, and the recipient later fetches it. If you ever need to see how this works in practice for your own domain, the knowledgebase has guides for configuring mail clients and DNS records.
The lesson for site owners today
Email works because of a few simple conventions, and it stays reliable when those conventions are set up properly. Using an address on your own domain, with SPF, DKIM and DMARC records in place, helps your messages reach the inbox. Zebra Hosting offers business email hosting so you can use addresses on your own domain, set up automatically within minutes of payment.
