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E-mail address

An e-mail address uniquely identifies a mailbox on some host on the Internet. A modern e-mail address is of the form username@domainname, where the username usually identifies the individual and the domain name identifies the machine providing e-mail services. In most cases this will be a free e-mail provider such as Hotmail, the name of an Internet Service Provider or the name of the organisation which owns the mail server.

Valid characters in both the username and domainname part are limited to ASCII, excluding the following characters:

Mappings from unicode to the permitted ASCII characters exist, although these are most commonly seen in Asia and not widely used in Europe or North America. An e-mail user can optionally surround his or her e-mail address with angled brackets and add a descriptive phrase, for example "ap118@ficticiousdomain.ext" could become "John Smith ".

Mail addresses should rarely be considered authoritative, because of the nature of SMTP it is very straightforward to forge an address or enter an invalid address when connecting to a server. This is most commonly seen when dealing with spam messages. If security is required, messages should be digitally signed or encrypted.

The Need for E-mail

Having your own e-mail address is considered an essential part of life in cyberspace and is required for almost everything other than viewing pages. Making online purchases, subscribing to paid content, posting in web logs or Internet forums, participating in Usenet newsgroups and many other tasks will require a valid e-mail address. Despite once being considered part of "geek culture", not having an e-mail address can seriously disadvantage a person. For this reason, many governments in modern countries are undertaking initiatives to give e-mail addresses to public servants and school children.

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