Never allow your email address to be posted or listed on a publicly available web page. "Spiders" and web "crawlers" routinely "harvest" email addresses from web pages in a effort to build a collection of email addresses to send junk email to.
Never ask to be removed or attempt to unsubscribe from a spammer's list. The only exception to this rule, is if you originally signed up for that particular list or asked to receive updates. But if you never asked to be part of a particular mailing, why would you ask to be removed? This is a common ploy spammers use to validate email addresses. If you respond, that proves to them that your email address is alive and active, and that you are receiving their mail pieces. Responding only encourages them to sell your email address to other spammers, and will ultimately increase the amount of junk email you receive.
Never open or read junk email. Believe it or not, even if you never respond, but merely open a junk email, there could be special HTML code contained in that email message that will report back to the spammer that you opened or read the message. This provides validation to the spammer that your email address is alive and active, and you can bet you will start receiving more spam! Be sure to turn off your email program's Preview Pane feature, as this is essentially the same as "reading" a message.
Avoid contests, special offers, free offers, and chances to win -- anything. These are gimmicks to get you to reveal your email address so they can send you special offers. Many free ecards (electronic greeting cards) are also ways companies collect email addresses.
Never post to a newsgroup or email list using your private email address. Many spammers watch these posts in order to harvest new email addresses.
If you are a contact for a registered domain, do no list your private email address, instead use a generic common mailbox for this purpose. Create a public address such as "DNS@yourdomain.com" or "help@yourdomain.com".
Guard your computer against trojan spyware software. Never open any attachments you don't explicitly trust. Some "fun" emails are often a ruse to steal email addresses or track your behavior on the internet. (ex. "friendly greetings program") The use of both anti-virus and personal firewall or anti-spyware software is strongly recommended.
Use a free Yahoo or Hotmail account as your public email address. Reserve your private email address for friends and select associates. Never sign up for special offers using your private email address.
If the junk mail level has gotten out of hand in your Inbox, consider changing your email address. Refer to rules 1-8 above to extend the time before spammers discover your new identity.