After I wrote a column about how to reduce the amount of spam (junk e-mail) in Google's Gmail, Don Wenig of Tucson, Ariz., voiced the frustration of many e-mail users.

"I just wish I knew how these creatures got my address," Wenig said.

I took that to heart, and here is a list of the ways that spam producers get your e-mail address and what you can do to prevent it.

Don't respond to an e-mail from someone you don't know, not even to "unsubscribe" from an e-mail list that sends you unwanted information. It only confirms that your e-mail address is a good target.

Don't download any e-mail images that weren't initially displayed by your e-mail program. That also confirms that your e-mail address is available to spam.

Don't sign up for any online service that says it will remove your name from spam lists. Chances are, the site is run or monitored by spammers.

Don't respond to attention-grabbing e-mails, such as a "delivery failure message" for an e-mail you didn't send, or a message that says you requested something that you didn't. They're just bait.

Don't let an automatic e-mail response go to everybody. When on vacation, set your e-mail to respond with an "I'm-not-here" message only to e-mails from people already in your contacts list. Otherwise the automatic response may confirm your e-mail address to spammers.

Don't be fooled by phishing e-mails that urge you to use an e-mail link to a website where you can correct or confirm something about your e-mail, bank account, credit cards or other personal material. These people are trying to steal your personal information.

Don't participate in online contests that offer cash prizes or free trips in exchange for your e-mail address. This is a bit like giving out your street address and telephone number whenever you buy a lottery ticket, something most people would never do.

Don't use your main e-mail address in online forums. Spammers scan these forums with programs called "Web crawlers" that copy e-mail addresses (typically they copy anything that contains the "@" symbol.) Protect yourself by adding phony details to your e-mail address, such as inserting the phrase "delete_this" in the middle of the address. You won't fool any people, but you might trick an automated Web crawler.

Don't give out your real e-mail address without considering two alternatives. You can set up a secondary free e-mail address to give to websites; if that account becomes clogged with spam you can close it. Or set up "disposable e-mail addresses," temporary addresses that forward e-mail to your real address. See

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