Bill Gates was wildly optimistic when he said in 2004 that the problem of spam would be "solved" by 2006. The volume of junk e-mail transmitted worldwide is still enormous. But a remarkable trend is underfoot, according to Brad Taylor, a staff software engineer at Google: The number of spam attempts – that is, the number of junk messages sent out by spammers – is flat, and may even be declining for the first time in years.

Google won't disclose numbers, but the company says that spam attempts, as a percentage of e-mail that's transmitted through its Gmail system, have waned over the last year. That could indicate that some spammers have gotten discouraged and have stopped trying to get through Google’s spam filters.

Google data suggests that incoming spam (the red line) has flattened or declined for the first time in years. (The blue line represents the percent of spam that is missed by Gmail filters and reported by users as arriving in their inboxes.)

Image: GoogleOther experts disagree with Google, pointing out that overall spam attempts continue to rise. By most estimates, tens of billions of spam messages are sent daily. Yet for most users, the amount of spam arriving in their inboxes has remained relatively flat, thanks to improved filtering.

Brad Taylor is on the front lines of the war on spam. He has served as the chief watchdog of Google’s spam filter since 2004, when Gmail first launched. His history with spam goes back much further, though: He's been fascinated with it since 1994, when he received his first spam e-mail at a work account. Before he joined Google, he worked at an anti-spam startup.

Taylor denies he's obsessed with junk mail, but his actions speak otherwise: For his own amusement, he Googles the gobbledygook at the bottom of spam messages to see where the text comes from. (Some are from Harry Potter books, he says. He also found one that was an English translation of a Russian science-fiction novel).

"It's fun," he says of catching spammers. "Sometimes I think, 'Oh, wow, that guy's really clever.'"

The chase may be exciting, but Taylor's real dream is to return e-mail to the "pristine experience it used to be."

Chenxi Wang, an analyst at Forrester Research, scoffs at the idea that spam attempts could be on the decline.

"I'm seeing that the overall trend is up," Wang says. "We're not seeing a drastic increase, though. And we're also seeing an increase of targeted spam instead of blanket spam that hits everybody in a large population. Today, for instance, you see spam messages on saving (on) prescription drugs targeted to seniors."

For its part, Yahoo, too, says the overall amount of spam transmitted is on the rise, but the percentage of spam that reaches its users’ inboxes is down. (Yahoo would not disclose specific numbers.)

Regardless of the overall spam attempts, David Daniels, vice president of Jupiter Research, predicts the number of spam messages that actually reach a typical inbox will remain roughly flat over the next three years. And for most people, that's what really matters.

"We're forecasting that the number of spam messages that annually reach the average inbox will hit 4,351 in 2007. For 2010, we think that number will essentially be flat at 4,403. The growth will be very, very small," Daniels says.

There are a couple of reasons for the lack of growth in spam deliveries. For one, e-mail providers like Google, Yahoo, AOL and Microsoft's Hotmail use sophisticated filtering algorithms that are constantly updated based on spam reports from individual users. Google says it can delete all instances of a single spam message across the Gmail network in seconds.

New anti-spam technologies are also always under development, and there are already countless anti-spam services and technologies available to consumers, including disposable e-mail addresses.

It's by no means a perfect system, though. And spammers are, if nothing else, persistent.

In a bizarre twist, Daniels thinks that instead of receiving spam offers from penny-stock pushers, mailboxes will increasingly be filled with marketing messages that we choose to receive, such as promotional e-mails from a favorite clothing store or a bank. He thinks the average number of messages from marketers that individuals receive annually will grow from 2,715 in 2007 to 3,335 in 2010.

"We expect people to spend as much time on e-mail as they have, but we think people will receive more e-mail from legitimate marketers. So there will be more competition to get consumers’ attention in the inbox, but it will be more like competition between The Gap and J.C. Penney as opposed to The Gap and a Viagra salesman."