Why is the symbol @ used in e-mail addresses?

An e-mail address identifies a location to which e-mail messages can be delivered. The first electronic mail delivery engaging two machines was done in 1971 by Ray Tomlinson, a programmer at Bolt, Beranek and Newman, an engineering company in Cambridge, Massachusetts. He needed a way to separate, in the e-mail address, the name of the user from the machine the user was on. He wanted a character that would not, under any conceivable circumstances, be found in the user’s name. He looked down at the keyboard and chose the @ sign among various punctuation marks available on his Model 33 teletype keyboard. He had no idea that he was creating an icon for the wired world. Today, email is the most used application on the internet. Each e-mail account has a unique address. A general format for an e-mail address is: username@computer_name. The part before the @ sign is the local part of the address, the user name of the recipient, and the part after the @ sign is the domain part which is a host computer name.