When mailing to unknown parties; posting to newsgroups, mailing lists, chat rooms and other public spaces on the Net; or publishing a Web page that mentions your e-mail address, it is best to do this from a “side” account, some pseudonymous or simply alternate address, and to use your main or preferred address only on small, members-only lists and with known, trusted individuals.
Addresses that are posted (even as part of message headers) in public spaces can be easily discovered by spammers (online junk mailers) and added to their list of targets. If your public “throw away” address gets spammed enough to become annoying, you can simply kill it off, and start a new one.
Your friends, boss, etc., will still know your “real” address. You can use a free (advertising-supported) e-mail service provider like Yahoo Mail or Hotmail for such “side” accounts. It is best to use a “real” Internet service provider for your main account, and to examine their privacy policies and terms of service, as some “free mail” services may have poor privacy track records.
You may find it works best to use an e-mail package that allows multiple user IDs and addresses (a.k.a. “personalities”, “aliases”) so that you do not have to switch between multiple programs to manage and use more than one e-mail address (though you may have to use a Web browser rather than an e-mail program to read your mail in your “throw away” accounts – many free mail providers do not allow POP or IMAP connections). If you are “required” to give an e-mail address to use a site (but will not be required to check your mail for some kind of access code they send you), you can use “someuser@somesite.com” (somesite.com is a non-existent site, set up by the Internet standards to be used as an example that will never accidentally coincide with anyone’s real e-mail address, which is always a danger if you just make up one off the top of your head.).