The Creation of Network Mail
ARPANET, the original seed of what would later become the internet, was designed to share scarce computing time across different universities. It was not designed for communication among people. However, as ARPANET evolved, small applications were developed, like file transfer protocols and electronic mail, to facilitate the management of the network itself.
Ray Tomlinson, working for ARPANET, developed the software for electronic mail in ARPANET. In 1971 he wrote some code to exchange messages between computers owned by the same institution in a structured way. As in any communications system, the first step was to define the address for the exchange of communications. In a computer system, the address would include the name of the individual and the name of the computer system used by the individual. Tomlinson had the idea of introducing the symbol to separate the name of the individual from the name of the computer system. This was the perfect sign; being very rare, it would not be included either in the name of the individual or the computer system. This is how the most popular digital symbol came to be created. Creating this protocol was not part of Tomlinson’s job description, however. He was not instructed by his reporting line. He just thought it would be nice to facilitate the exchange of messages. One year later, the software developed by Tomlinson would be formally included in the ARPANET protocols that would be used not only inside one network, but in the ARPANET network of networks.
Network mail (as email was originally called) proved to be the most popular application in ARPANET. As early as 1973, three-quarters of the traffic in ARPANET was network mail.2 This is a good example of how networks tend to grow organically beyond the expectations of their creators.
The use of email grew in parallel to ARPANET and the internet. Emailing was popular first among ARPANET users; it later expanded to the wider community of universities and research centers and was eventually commercialized for the use of any interested user by internet service providers (ISP), commercial ventures that provided the service for a profit. ISPs would provide an email address to each customer.
By the end of 1995, the internet was used by only 16 million people worldwide (0.4 percent of the world population), but it was mature enough to go mainstream, just like its most popular service: email.