Clearswift Adds Anti-Spam to MAILsweeper SMTP Gateway

Security vendor Clearswift has released an anti-spam add-on capability to its MAILsweeper SMTP gateway product that employs Bayesian and heuristic techniques to improve spam detection rates and lower false positives.

The Anti-spam Solution of CS MAILsweeper learned about an organization as it tracks email traffic, thereby improving its detection and false positive rates over time. Clearswift sends out a keyboard blacklist update eight times each day from its CS spamActive database.

The product’s hybrid spam detection engine employs a hybrid approach of text analysis, heuristics and Bayesian classification. Customers have achieved over a success rate of over 90% with the tool, and reducing false positives to one in 1,000, the company says.

Anti-spam Solution allows messages to be classified as spam, not spam or maybe spam, with different results. Administrators have tight control over configurations for the end user, such as message annotations, spam thresholds and rule weightings.

The Bayesian Classifiers learn about the words used in spam and “not spam,” then assign probabilities to each based on the number of occurrences. Organizations can profile their own legitimate messages and apply those rules when they have a new message to process.

Heuristics check the structure of the message to check for the likelihood it is spam, such as whether the message is pure HTML-based or has text and an HTML body. Text analysis looks for words and phrases typically used in the subject lines and text of spam.

The system can handle 15,000 messages per minutes, says Greg Hampton, VP of U.S. marketing for Clearswift. The market is competitive, he noted, with some 120 companies offering anti-spam products, but much fewer building on an installed base such as Clearswift has with MIMEsweeper product, in use by 15,000 customers. CS MAILsweeper with the anti-spam solution is priced at $2,000 for 50 seats; the price per seat drops at higher volumes.