Then Ray Tomlinson came along.  In 1971, Tomlinson was an engineer at the Cambridge, Massachusetts, consulting firm of Bolt, Beranek, and Newman (BBN).  BBN had a contract from the Advanced Research Projects Agency (ARPA) of the U.S. Department of Defense to help in the development of ARPANET, an early network from which the Internet later emerged.  Staff at BBN had developed a program to leave messages to each other on an ARPANET computer at the company.  Tomlinson came up with the notion of combining this program with another program that transferred files among ARPANET computers around the country in order to send messages among these networked computers. 

To do this, however, he needed some means of distinguishing between messages intended for local recipients and those for people at some other location.  According to an article in Rensselaer Polytechnic Institute (RPI) alumni magazine, Tomlinson (RPI '63) came up with the @ sign "to indicate that the user was 'at' some other host." The rest, as they say, is history. 

But the history of the @ sign, in fact, pre-dates e-mail by many years -- around 435, to be precise.  Although the origin of the symbol has been long been disputed by scholars, Giorgio Stabile, a professor of the history of science at La Sapienza University in Italy,  recently documented its use in a letter written by a Florentine merchant in 1536.  In that letter, the @ sign represented an amphora, a standard-sized clay vessel used in ancient times to carry wine and grain in trade in the Mediterranean area.  Eventually, according to Professor Stabile, the use of the "@" in trade led to its contemporary meaning (prior to e-mail, that is) of "at the price of."  In 1885 it appeared on the keyboard of the first Underwood typewriter, from where it eventually made its way to today's standard computer keyboards. 

The @ symbol has many different names around the world.  In English, while still the "amphora" officially, it is most widely known as the "at sign."   The names in German (at-Zeichen) and Japanese (atto maak) are similar.  Spanish and Portuguese people call it the "arroba" and the French call it "arobase," (which translate as "amphora" in English).    Italians call it "chiocciola" (snail); Swedes know it as the "kanelbulle" (cinnamon bun), while to Czechs it is "zavinac" (a rolled pickled herring served in pubs).  In Hebrew it's the "shtrudel" (strudel), while, according to an article in the now-defunct Industry Standard, the Finnish word--"miukumauku"--translates charmingly as "the sign of the meow," recalling a curled-up, sleeping cat.

An account of the origin of the @ sign in Encyclopedie de la Langue Francaise (in French) - with a photo of the document discovered by Professor Stabile and a close-up of the @ sign in it.

Profile of Ray Tomlinson in Rensselaer Mag, September 2000. (Source of photo above.) 

"Ray Tomlinson:  Inventor of e-mail," by Daintry Duffy, Darwin Magazine (January 2002).

"Forbes Legends," by Sasha Cavender (a profile of Ray Tomlinson), Forbes (October 5, 1998).

"Ray Tomlinson: Inventor of e-mail."  An interesting profile with references.

Ray Tomlinson, "The First Network E-mail."  How it happened, a first-person account by the man who did it.

Tomlinson's listing on the site for the PBS television program, "Nerds 2.0.1."

"Where It's At:  Names for a Common Symbol," World Wide Words.  Discusses names for @ in various languages and history of the symbol. 

Karen S. Chung, "@ Summary," The Linguist, July 2, 1996.  A lengthy post summarizing an online discussion of the origins of and names for "@" with contributions from 105 people.  Original source material for several of the articles cited here. 

"@ Sign Invented in Italy," by Rossella Lorenzi, Discovery.com News, Aug. 1, 2000.  Posted on the FoRK Archive, August 11, 2000.

"merchant@florence wrote it first 500 years ago," by Philip Willan, The Guardian (UK), July 31, 2000.  

"The "at" (@) sign . . . is everywhere these days," a report on National Public Radio's All Things Considered, in RealAudio, July 31, 2000.  Includes an interview in English with Professor Stabile. (Note you will need to scroll about halfway down the page to find the link to this story.) 

Symbol Definition:  The "@" Sign, on Google Answers, October 24, 2002.

Profile of Giorgio Stabile on Encyclopedia Multimediale delle ScienzeFilosofiche (in Italian).

*An updated "encore presentation" of a popular Tech Tidbit first published on May 14, 2001.  Dead links have been removed.  Others have been updated and new ones have been added.