General Description of Electronic Mail
Electronic mail, sometimes called email, is a computer based method of sending messages from one computer user to another. These messages usually consist of individual pieces of text which you can send to another computer user even if the other user is not logged in (i.e. using the computer) at the time you send your message. The message can then be read at a later time. This procedure is analogous to sending and receiving a letter.
Originally, email messages were restricted to simple text, but now many systems can handle more complicated formats, such as graphics and word processed documents.
When mail is received on a computer system, it is usually stored in an electronic mailbox for the recipient to read later. Electronic mailboxes are usually special files on a computer which can be accessed using various commands. Each user normally has their individual mailbox.
It is straightforward to send electronic mail between users of different computer systems which are connected to major networks. Most major academic and research institutions and companies throughout the world can now be reached by electronic mail. In addition, a growing number of individuals can be contacted in this way. In the UK, most academic and research institutions are linked by a network called JANET (or SuperJANET). This is effectively part of the Internet, so email can be exchanged with most national and international networks.
All email systems have the ability to send, receive and discard mail. Most systems have facilities for storing mail which is to be kept rather than discarded. lt is important to discard mail which does not need to be kept, as it uses storage space on disks. Mailboxes can soon accumulate a large number of mail messages making it difficult...