(MONEY Magazine) – Spam, the unsolicited e-mail pitches that clog your mailbox, is an annoyance that's only getting worse. I have four separate e-mail addresses (at AOL, Earthlink and Yahoo), and on average I get at least 50 spams a day. Frankly, the pitches for Viagra and even the pleas from Nigerian "dignitaries" don't bother me. But recently some of the dreck that's found its way into my mailbox is so offensive that I've decided to fight back. What I've found is that because spammers regularly mutate their messages, you need several solutions to alleviate the problem. I say alleviate because stopping spam is all but impossible. Here's my plan for cutting it to a manageable level.

Guard your name. Don't give your e-mail address to any website unless you must. If you do, read the site's privacy policy to make sure it won't sell your name--or, if it will, that it lets you opt out. Once you register at a site, pay attention to any notices. In April, Yahoo told users that it was resetting their marketing preferences to allow the site to send out unsolicited pitches. When I checked my account, I found that Yahoo had enrolled me in 14 categories of junk mail, from "find a job" to "meeting someone special." You have 60 days from the date of the notice to opt out (in the e-mail section, click on Options and then Account Information). Make sure you scroll to the bottom of the page to say no to solicitations by phone or regular mail.

Even if you never divulge your address, spammers can find you by generating random addresses in a so-called dictionary attack. So never open e-mail from a stranger--doing so can trigger a return receipt, confirming that the sender has reached a live body. Never hit Opt Out, which is often a ruse to draw a reply.

Enlist allies. Most ISPs and portals have a filter that will trash e-mail or sort it by sender or number of recipients, and I've found them to be helpful. Yahoo will funnel bulk e-mail into a separate folder, where you can read it or ignore it (the box empties every 30 days). One problem is that I want some of that bulk mail--the New York Times Circuits section, for example. To redirect it into my In box every week, I had to open the message and click Send to Yahoo for Review.

Similarly, Earthlink's filter--called the Spaminator--redirects bulk mail into a separate folder (go to the message center and click on Stop Junk Mail to turn it on). I find that it does a decent job of separating the wheat from the chaff, but some porn still finds its way into my mailbox.

With AOL (run by MONEY's parent company), the spam filter will block e-mail only from addresses you name. Every time you're spammed, copy the address into Mail Controls. Even though garbage gets through, I feel like I have a modicum of control. MSN Hotmail's filter blocks all bulk mail unless you say otherwise. You can also get mail only from people in your address book.

Activate internal defenses. Your e-mail software may also have spam filters. Microsoft Outlook and Outlook Express, Eudora and Apple's OS X e-mail program all let you block e-mail by sender or by the keywords you select.

Bring in outside help. If these steps don't do it, you can buy one of the many antispam software programs available. My favorite is SpamKiller 2 from McAfee (www.spamkiller.com; $30), and not just because of the ricocheting-bullet sound it makes when eliminating spam. It intercepts and reroutes junk to a killed-mail file using nearly 1,500 key words, phrases and countries of origin. You can edit those filters--I deleted "money"--add your own and download free updates. SpamKiller will also help you submit a complaint to a spammer. Want to completely clamp down on spam? Set the program to receive e-mail only from addresses that you list. Try SpamKiller free for 30 days. It's well worth it.