Tomlinson was one of a group of scientists who were working on developing better computers. The scientists at his site were able to send a massage to a mailbox onthe computer on thire site. Other scientists could view the massage in the mailbox. But there were other computers at other sites where scientis were working on the same project. Tomlinson idea was to figure out a way to deliver massage to mailboxs on those remote computers. He used to the @ sign to dentify massage that were headed out of the local machine to the more distant ones. That was the start of the emailing system that we still use today.