Security publication Virus Bulletin has issued the results of its latest round of spam blocking tests.

The September edition pitted 12 spam-blocking suites against a series of messages collected in the wild. The products are tested for the ability to block spam, and to prevent 'false positives' that block legitimate emails.

Nine of the 12 vendors passed the test, but ClamAV with Sanesecurity signatures, SPAMfighter Mail Gateway and modusGate failed.

Top honours went to the McAfee Email and Web Security appliance, which was awarded a platinum-level certification.

Five products earned the gold-level certification, namely BitDefender Security for Mail Servers, MessageStream SaaS, M+Guardian, Kaspersky Anti-Spam and McAfee Email Gateway.

Webroot E-mail Security SaaS, FortiMail and Microsoft Forefront all picked up silver certifications.

The results were an improvement for several vendors on the last Virus Bulletin spam tests in July, in which two products were awarded platinum, but only one was able to claim gold.

"The benchmarks used for this test were stricter than previous tests, making the achievement of these products all the more impressive," said Virus Bulletin anti-spam test director Martijn Grooten.