E-mail marketing is able to establish the kind of personal contact taht is impossible using any other medium. And it's way cheaper too, than big-dollar, bang-the-drum TV ads.

When you're at home alone, do you close the door when you go to the bathroom?

This nosy question appeared on the envelope for a come-on subscription to Psychology Today way back in the 1980s. It was one of the most successful direct mail campaigns of all time. And it kicked the pants of marketing directors everywhere who believed that only big-dollar, bang-the-drum TV ads could make cash registers ring.

The sexy little secret about e-mail marketing is that it's touchy-feely. You grope. It gropes back. A dialog is established.

New generation, same story. After torching billions of dollars in Super Bowl commercials and multimedia advertising blowouts, Internet companies big and small are learning there's a better way: e-mail.

Let's not prettify the term. We're talking about spam. Classy? No, it puts you in the company of hair-growth hucksters, Florida condo peddlers, and talk-dirty-on-the-phone-for-$1-a-minute rackets. But drop your airs for a moment and consider its magic. E-mail is cheap. It's personal. It's extraordinarily well targeted. It's effective. And it talks back.

What do you think? YES

Better yet, it's heading uptown. No less than PepsiCo, Borders, Toyota, and have put e-mail to work in the past year with unassailable success. It's getting slicker, too. Savvy upstarts now fill their come-ons with personalized audio messages, color photos, instantly redeemable online incentives, and other bait.

It works better than you'd believe. The click-through rate on boring banner ads has dropped to less than 1 percent, while e-mail responses reach as high as 10 percent.

And did we mention costs? Mail-order catalogs can run $1 a pop. Offline direct mail campaigns cost an average of $20,000 just for creative and production services, never mind the mailing lists and postage. They typically require three months in planning and development. Yet you can launch an e-mail campaign for less than the price of your suit.

The sexy little secret about e-mail marketing is that it's touchy-feely. You grope. It gropes back. A dialog is established—an impossible feat using any other medium.

Not only can you track how many people open your message, but you can see who clicks to the Web site and learn what they do when they get there. Because an e-mail campaign moves quickly, you'll discover whether it's working within 48 hours. If a campaign stalls, tweak it, then float a more effective message the very same week. You talk; it talks back.

eBags, which sells luggage and accessories, claims that judicious use of e-mail has helped it lower marketing costs by two-thirds, while sales have more than doubled. In December 1999, the company sold 18,000 bags online; last December it sold 43,000.

Only months ago, Jive Records sent 200,000 fans of the teen band 'N Sync a video message about the just released No Strings Attached album. Recipients could hear band members speak and listen to a snippet of songs. Fans went wild: 34 percent of recipients downloaded the video. Of those, 88 percent clicked on one of the links. Thousands forwarded the e-mail to friends. In a world where marketeers break out the bubbly on a 1.5 percent response rate, Jive sent heads spinning.

But is the party getting too large? By some estimates the average household will receive nine electronic come-ons per day by 2004. Already spam is about as welcome as a jury duty notice. Marketers must learn to sneak their come-ons into messages people want. Content is key. Those who get it right will get rich.

Wendy Taylor is editor of Ziff Davis Smart Business; Marty Jerome is a contri buting editor. E-mail them at taylor&