E-mail or electronic mail is a digital message that is sent through a computer network. The first electronic mail was sent to the then ARPANET in 1982 ( RFC 561) . In order to receive e-mail, both the sender and the recipient had to be online in the early e-mail system. Today's e-mails do not have this problem. E-mail servers receive and store mail and send it later. The user or recipient, or the computer, does not need to be online, as long as there is an active e-mail address on an e-mail server.