Tomlinson was one of group of scientists who were working ondeveloping better computers. The scientists at his site were able to send a message to a "mailbox" on the computer on their site. Other scientists could view the messages in the mailbox. But there were other computer at other sites where scientists were working on the same porject. Tomlinson's idea was to figure out a way to deliver messages to mailboes on those remote computers. He used the @ sign yo identify messages that were headed out of the local machine to the more distant ones. That eas the start of the emailing systems that we still use today.