The study titled, "Spam Index Report -- Comparing Real-world Performance of Anti-Spam Technologies," evaluated eight anti-spam technologies from the three main technology classes including filters, real-time black list services and challenge-response servers, using the Spam Index, a new method in anti-spam performance measurement that uses users' real-world experiences.

The report found that the best performing anti-spam technology is challenge-response, based on that technology's lowest average Spam Index score of 160. The 160 score is 50 percent less than the next lowest average score of 316 achieved by hosted services, indicating that challenge response is twice as effective as hosted services for prevention of spam, says Brockmann. The worst performing technology was filter-based ISP solutions, with a Spam Index of 442.

"Email is consistently recognized as the most important communications service affecting job performance in virtually all industries and all job roles. Yet spam continues to detract from user productivity by providing too many inappropriate, anonymous, bulk and irrelevant messages," says Peter Brockmann, president of Brockmann & Company. "The Spam Index is the first objective real world tool that takes into account real-world user experiences in comparing the effectiveness of anti-spam technologies. The Spam Index uniquely provides the link to real-world user experience, something missing in earlier technology evaluations."

Results of the report are based on the responses of 520 business users of email services from around the world who participated in a seven minute online survey.