The firms are supporting the emerging standard known as domain keys, which block fake e-mails by validating the sender with a digital signature.

Spammers hide their identity by using a false, or spoofed, address in the millions of messages they send out.

The technology, called the DomainKeys Identified Mail (DKIM), will be available to millions of Yahoo Mail users worldwide in the coming weeks.

It is a big step forward for consumers in defence against the bad guys," John Kremer, vice president of Yahoo Mail, told Reuters news agency.

Several ways. First, it can allow receiving companies to drop or quarantine unsigned email that comes from domains that are known to always sign their emails with DomainKeys, thus impacting spam and phishing attacks. Second, the ability to verify sender domain will allow email service providers to begin to build reputation databases that can be shared with the community and also applied to spam policy. For example, one ISP could share their "spam vs. legit email ratio" for the domain www.example.com with other ISPs that may not yet have built up information about the credibility and "spamminess" of email coming from www.example.com. Last, by eliminating forged From: addresses, we can bring server-level traceability back to email (not user-level - we believe that should be a policy of the provider and the choice of the user). Spammers don't want to be traced, so they will be forced to only spam companies that aren't using verification solutions.

Those ubiquitous Viagra ads have been disguising themselves as e-mail newsletters, the kind you get to find out the latest airline deals or keep up with your fantasy football team.

Spammers haven't actually broken into legitimate marketers' computer systems to send out the messages. Rather, like the phishing scams that lift the code off the real Web sites of financial institutions, spammers have tweaked legitimate e-mail and sent them through normal spam channels.

The technique appears aimed at bypassing human and software controls. Recipients might not immediately realize they are opening spam, and anti-spam filters might not be able to aggressively block them for fear of blocking legitimate newsletters as well, anti-spam experts say.

These messages started appearing a month ago, and so far, they have been relatively small in numbers, said Doug Bowers, senior director of anti-abuse engineering at Symantec Corp., a vendor of anti-spam products. He suspects spammers are fine-tuning their techniques to see what works.

Mass e-mailers traditionally bump up their activity as the year winds down. But this year, the amount of junk messages could be unprecedented, companies that make spam-busting tools say. And senders of unsolicited ads are already celebrating the close of the harvest season and the approach of Christmas.

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There's a holiday spam spike every year, because people are more likely to open the messages, experts said. Consumers are shopping online more, are desperate for gift ideas and expect electronic greeting cards. Spammers exploit all of that by sending fake order confirmations and e-cards and, of course, suggesting their products as gifts.

"People sell fake Rolexes via spam e-mail, and fake Rolexes make good holiday gifts," Pao said. "We expect that the amount of overall holiday-related spam to increase up to 50 percent during the week of Thanksgiving and continue through New Year's. It looks like this could turn out to be the largest, and longest, holiday spam season ever."

New tricks
There are a number of reasons for the rising tide of messages, experts say. For one, spammers are constantly looking for and finding new ways to reach unsuspecting people, said Miles Libbey, a product manager at Yahoo. "We continue to work tirelessly to make sure junk mail goes into the spam folder," he said. Yahoo, which operates one of the most popular free e-mail services, is using technology and collaborating with others to bust spam rings, Libbey said.

Analysis of the contents of millions of e-mails has revealed that less than 4% is legitimate traffic.

Further work has shown that most of this junk mail is originating on hijacked home computers.

E-mail security firm Return Path said 99% of the computers it monitors that send mail have been taken over by spammers or virus writers.

Return Path reached its estimate by calculating a "reputation score" for the 20 million net addresses of those machines.

Blue Security, which debuted its spam-fighting service last summerand built up a user base of more than 500,000, decided to wave the white flag after its servers were knocked offline by an aggressive denial-of-service (DoS) attack it claimed was launched by a deep-pocket Russian spammer tagged as "PharmaMaster."

May 3, in an attempt to get out the word about the DoS, Blue Security repointed its domain to an unused blog on Six Apart's TypePad blogging service. Within minutes, PharmaMaster attacked the blog with another DoS, which brought down Six Apart and left millions without access to their blogs. Blue Security's domain name service provider, Tucows, was also hit with a DoS and knocked offline for several hours; Tucows going down took thousands of Web sites it hosts with it.

Wednesday, Blue Security said it had to give up because it couldn't sustain the fight against spammers. "Several leading spammers viewed [us] as a strategic threat to their spam business," Eran Reshef, Blue Security chief executive wrote in the message posted to the company's site.

"After recovering from the attack, we determined that once we reactivated the Blue Community, spammers would resume their attacks. We cannot take the responsibility for an ever-escalating cyber war through our continued operations.

"If AOL or another ISP decides that someone's a spammer, then no e-mail from that individual gets through," said EFF attorney Cindy Cohn, whose group opposes the AOL plan. "But there's a fundamental difficulty at the heart of the spam debate: The only one who knows what you want delivered in your inbox is you."

For years, e-mail users complained that torrents of unwanted messages clogged their inboxes and crimped their productivity. Now, e-mail users, marketers and mailing list operators are more worried that spam filters are blocking out too many wanted messages.

AOL isn't the only company to face charges that it improperly blocks legitimate messages. But, as the world's largest ISP for years, it has long borne the brunt of complaints from mass e-mailers over the problem.

Those concerns are seeping into the debate over a planned AOL program, set to go live in the next month, in which approved e-mail senders pay to guarantee delivery of their messages.

Economic and Financial Crimes Commission (EFCC) has again begun its clampdown on scammers in Lagos State.

In its latest move to check activities of the fraudsters, the anti-graft agency swooped on cyber cafes at FESTAC Town last week and arrested over 87 of operators and fraudsters who use the facilities to send scam letters.

A competent EFCC source said the exercise was necessary following reports from prominent residents of the area alleging an increasing number of such cyber cafés and how their activities were becoming a threat to the neighbourhood.

The official, who would not want his name in print, said after the mop-up, over 87 persons, including operators and scammers, were arrested. He added that most of them had made useful statements to the agency and would soon be charged to court.