e-mail 
electronic mail 
Whenever you send messages to people using a computer and they read it later, you've sent a piece of e-mail. You can send e-mail in several ways: across a local area network (LAN), via the Internet, or through a proprietary online service such as CompuServe or America Online, and you can send it to a single recipient or to a whole slew of them. But all e-mail behaves pretty much the same way: you send it to a virtual mailbox, and the recipient picks it up or uses software that does it automatically.