1. What are junk, chain, and hoax email?
Junk email is closely analogous to the junk mail that we all get in the post. Basically it is any email that is sent out without regard to whether the recipient is actually interested in it. It may be advertising goods or services, it may be expounding an ideology, it may be anything else that you don't want to receive. Some of it, eg that advertising availability of pornographic material, may be offensive to many people. The main difference between this and postal junk mail is that sending it out by email is vastly easier and cheaper than doing it through the post. It is therefore available to a much wider range of senders, some of whose rationality may be open to question. It also means it can be sent completely indiscriminately. Sending the same mail to large numbers of people is known as "spamming".
If you receive such mail, it is important that you realize that, in general, you have not been specially targeted. There are many companies (mostly in the US) which sell lists of email addresses, which they gather indiscriminately from any source they can find. If you send email to mailing lists, if you take part in newsgroups, if you request information from on-line sources, you will find yourself on their lists.
Chain email is when you are asked to send a particular message to a number of other people, who are also asked to send it on. These messages can ostensibly for "good luck", to advertize a "worthy cause" or "pyramid selling" schemes.
One particularly popular form of chain mail is in the form of hoax virus warnings. The message usually purports to alert you to the existence of some new virus and urges you to pass on the message to everyone you know. Do not pass on such virus warnings. IT support staff normally keep closely up to date with genuine virus problems and, if appropriate, may occasionally issue warnings by email. For more information on virus hoaxes, see the OUCS virus information pages.