Electronic mail, most commonly referred to as email or e-mail since ca. 1993, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the same time, in common with instant messaging. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need connect only briefly, typically to a mail server, for as long as it takes to send or receive messages.
An electronic mail message consists of two components, the message header, and the message body, which is the email's content. The message header contains control information, including, minimally, an originator's email address and one or more recipient addresses. Usually additional information is added, such as a subject header field.
- http://en.wikipedia.org/wiki/Email
- 9 Rules for Emailing from Google Exec Eric Schmidt, Eric Schmidt, Jonathan Rosenberg. Time, September 24, 2014.
