Computer researcher Paul Graham got an unwelcome review last week on his technical article about software that blocks junk e-mail, or spam -- a trade publication's e-mail system wouldn't accept the story.
Computer administrators fished his submission from the system, and Graham said it was the second time since January he has been thwarted by digital sieves called spam filters. Others will share his experience as companies battle a tidal wave of unwanted e-mails among the billions sent daily, he and other software experts said.
Spam often pitches prescription drugs, sex-related products and get-rich-quick offers. Two-thirds of spam may carry deceptive or false claims, the US Federal Trade Commission said this month, and a Ferris Research study said spam may cost US companies and other organizations US$10 billion this year. The catch is that some spam filters are imperfect, sometimes mislabeling valid messages as undesirable and causing those notes to go unread.
"As more and more people install spam filters, more e-mails will get blocked," said Graham, a former Internet company executive and now an author in Cambridge, Massachusetts.
Spam filters work in several ways. Some seek words used often in junk messages. Others use complex mathematical formulas to examine the content of an e-mail and calculate the odds that it's spam. E-mails flagged as spam are set aside in a file or destroyed, depending on the program. The rate of mislabeled legitimate messages is debated.
Assurance Systems, a closely held adviser to marketers on e-mail, estimates 15 percent of desired e-mails sent by marketers don't make it to customers. Companies that make the software say they have so-called false positive rates of less than 1 percent.
"The problem is pretty huge," said Bill Nussey, chief executive of Silverpop Inc, a closely held e-mail services company based in Atlanta that has clients including Weather.com and the home-furnishings retailer Bombay Co.
Mislabeling legitimate e-mail concerns Microsoft Corp, which runs the MSN network, the second-largest US Internet service by subscriber, said Larry Grothaus, who helps market MSN services.
"It's something we take great steps to avoid, because if you start blocking mail people want, they just turn off the anti-spam technology and don't use it," he said.
Microsoft has upgraded junk-mail protection in its MSN and Hotmail e-mail services in the past few months. Other Internet service providers including AOL Time Warner Inc's America Online, the world's biggest Internet service, also have upgraded junk e-mail protection. AOL, Microsoft and Yahoo Inc have formed an alliance to fight spam.
About 30 companies sell or give away spam filters, according to Radicati Group Inc, a consulting firm. Sales of anti-spam software and services are expected to be US$2.4 billion by 2007, an almost fourfold increase from US$653 million this year, according to Palo Alto, California-based Radicati.
"They all claim to have the secret sauce," said Jim Nail, an analyst at Forrester Research Inc a technical consulting firm.
Companies that make filtering software, including Symantec Corp and closely held Postini Inc, say legitimate companies have nothing to fear from filtering programs.
"Filtering will get refined," said Chris Miller, a group product manager at Symantec, the largest maker of software that guards against computer viruses. "False positives will go down."