Report: ISPs Block 17 Percent of Legit E-mail

Top Internet service providers blocked 17 percent of legitimate permission-based email in the first half of the year, according to a report issued by Return Path.

The company, which helps email marketers make sure their mail gets through, said the so-called false-positive rate at the top dozen ISPs in the first two quarters of the year dropped 2 percent from the fourth quarter of 2002 and 5 percent from the third quarter.

While improving, the Superior, Colo., firm said email improperly blocked by stringent filters at ISPs represented a major challenge for the email marketing industry, as the consumer backlash against spam leads ISPs to aggressive action against bulk email. Many email marketers have complained that the filters swoop up their legitimate email messages along with spam.

Return Path based its findings on nearly 10,000 email campaigns it monitored for clients using its Mailbox Monitor service. Return Path acquired Mailbox Monitor when it bought Assurance Systems in June.

Return Path found that the false-positive rate varied wildly at ISPs, from as low as 1 percent to as high as 46 percent. Among major ISPs, AOL gave email marketers the most fits, with a 25 percent rate. AOL, struggling to hold onto its 28 million subscribers, has made its robust spam-fighting capabilities a key part of its marketing. AOL has said that spam is its top consumer complaint by far.

Interestingly, Earthlink, which has vied with AOL for top anti-spam credentials, had one of the lowest rates at 7 percent. Yahoo took top honors with a mere 4 percent false-positive rate. MSN’s rate was just under 10 percent.

Return Path found catalogers most vulnerable, suffering a non-deliverability rate of more than 40 percent. Software also suffers a high number of undelivered email, with nearly a third not getting through. In contrast, Return Path found clients in retail, software and non-profit industries had non-deliverability rates under 10 percent.