Though still rare, challenge-response e-mail systems have gotten the attention of e-mail marketers as another threat to getting their e-mail delivered.
Challenge-response systems are a new way to protect e-mail inboxes from the flood of spam. They work by treating every piece of mail from an unknown sender, often defined as someone not in a user's address book, as suspect. Mail from unknown senders is deposited in a suspect-mail folder, and the sender receives a “challenge” message to ensure the sender is not a computer. This is accomplished via a link to a Web site that asks the sender to enter a numeric code seen on the screen.
E-mail marketers have eyed such systems warily because computers generate commercial e-mail and consumers rarely put businesses in their address books.
“I would describe challenge-response as a blunt instrument,” said Dave Lewis, vice president of deliverability management and ISP relations at San Mateo, CA, e-mail service provider Digital Impact. “The net impact, fortunately, has been pretty insignificant.”
Of the major ISPs, only EarthLink offers a challenge-response option. The system, called SpamBlocker, has not proven overwhelmingly popular. Since its debut in May, just 5 percent of EarthLink's 5 million subscribers use SpamBlocker, company spokesman Jerry Grasso said.
EarthLink aims to sign up 1 million members by next May, thanks to more aggressive advertising of SpamBlocker.
“What we tell e-marketers is that we're not making any choices for our customers,” Grasso said. “We put it completely in the hands of our customers.”
In addition to EarthLink, some small software companies offer challenge-response systems. Based on current adoption, some industry analysts doubt whether challenge-response will have a noticeable effect on commercial e-mail.
“I don't think it's a major issue for now, and even if it became a bigger issue, people who use challenge-response likely didn't want to receive what you were sending anyway,” said Jared Blank, an analyst with Jupiter Research.
Despite the low adoption, some e-mail service providers are watching challenge-response as another potential delivery obstacle.
“If it continues to spread, you have to be conscious of this,” said Michael Della Penna, chief marketing officer at New York e-mail marketing firm Bigfoot Interactive. He said Bigfoot is “seeing a handful for every million [e-mails] going out the door.”
For now, Bigfoot Interactive and other e-mail service providers are responding to challenges manually. Bill Nussey, chief executive at Silverpop, an Atlanta-based e-mail marketing firm, said such labor-intensive approaches made sense for the dozen challenges Silverpop now gets for a mailing of 250,000, but might not if challenge-response gains consumer traction.
“The bottom line is challenge-response firms are going to be just like the ISPs,” he said. “They're going to let the customers decide.”
Mailblocks, a Los Altos, CA, provider of a Web-based e-mail service that uses challenge-response, on Oct. 20 released a briefing paper for e-mail marketers to learn how challenge-response works and what steps they can take to reach their customers.
Susan Bratton, vice president of sales and marketing at Mailblocks, said the background paper was part of an effort by the company to educate marketers and customers.
“It's such a new concept that everyone is interested in understanding how it works, how it affects the consumers and what e-mail marketers need to do to continue to get their legitimate e-mail delivered,” she said. Bratton would not say how many people have signed up for Mailblocks since its debut in March.
Among the suggestions Mailblocks proposes are to use a single from and reply-to address instead of using different addresses to help track campaigns. A single address lets receivers easily add marketers to their address books.
“If there's any silver bullet out there, it's getting the consumer to add a mailer to an address book,” Lewis said. Sounding a note of caution, he added, “None of us are terribly optimistic that is something that's going to be widely adopted.”
Lewis said he doubted challenge-response would catch on with consumers because it requires too much effort and often diverts wanted e-mail.
“The fact that you haven't had stronger adoption at this point is a pretty good indication that consumers are recognizing that it's not all that it's cracked up to be,” he said.
