Opt-out attempts
Responsible marketers who use unsolicited mass e-mail as their medium of choice always provide a way out, usually in the form of a Web link or a valid reply address. In our experiments, only the most egregious porn spam didn't offer any opt-out process. But that's not the same as providing an opt-out process that actually works.

A persistent story says that clicking unsubscribe links serves only to confirm your e-mail address and make it more valuable for spammers. During my tests, however, I used a single address to unsubscribe from more than a dozen suspect spam notices. The e-mailbox remained empty for two months except for two administrative notices from the service that provided the in-box. (Be warned: That experience may not be typical. If in doubt, don't send anything that will confirm your e-mail address to a spammer, especially if you don't recognize the company sending the newsletter.)

Here are some other approaches that may minimize unwanted e-mail once you receive it.

Custom spam filters
Effectiveness: A
Most e-mail providers include stringent filtering tools, which work well if you take the time to learn them. It's possible in AOL, for example, to accept incoming mail only from senders already listed in your e-mail address book. This trims unwanted e-mail down to nothing. Of course, this option may block messages from friends with new e-mail accounts, too, so it's a double-edged sword.

Automatic spam filters
Effectiveness: B
Your e-mail provider almost undoubtedly maintains a list of known spammers and offers to filter them. Excite Inbox does this automatically; Hotmail makes it an option. Your ISP may provide the service automatically too; check at its site to see. But in my experience, these services provide checkered results. Hotmail's default filter settings blocked only about two-thirds of junk e-mail to one of my test accounts.

Unsubscribing
Effectiveness: C+
True, if you unsubscribe to a piece of mail from that e-mail, you run the risk that unscrupulous mass mailers will use that unsubscription as confirmation that the account is active, then continue with their evil ways. But in my experience over two months of testing, unsubscribing from newsletters and marketing made a lot of headway. I did find some exceptions. Some lottery sites required two unsubscribe messages, and I encountered these additional problems:

• E-mail errors
  The spammers' e-mail servers rejected many of my e-mail unsubscribe messages for a variety of reasons. One server reported, "Relaying not allowed," while another claimed, "User storage quota exceeded." (The latter, of course, indicates that I wasn't the only one trying to opt out.)
• Broken Web links
  "This is not spam!" It's a common refrain in opt-out messages, usually followed by something like this claim: "This e-mail is being sent to you because you indicated that you wish to receive it. If you do not want to receive further mailings, just click the remove link below." So far so good, except the remove link (http://3519285059/remove.html) is not a working URL. All told, six of my unsubscribe attempts met with broken Web links; most from fly-by-night operations whose free Angelfire pages suddenly disappeared.
• Server errors
  While attempting to unsubscribe from MP3.com's newsletter, I encountered repeated internal server errors caused, the site told me, by "an internal error or misconfiguration [that made the site] unable to complete your request."

Blocking individual senders
Effectiveness: D
In Microsoft Outlook's Message menu, there's a Block Sender option that stops any future e-mail from a specific account. Most Web mail in-boxes offer the same option. This works well for keeping e-mail stalkers out of your hair, but it's useless against most spammers, who use a different address every time they send a message.

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