Cloudmark on Monday announced a service called StorageScan, designed to help ISPs clean old spam messages out of their customers\u2019 e-mail boxes.Despite the fact that ISPs deploy anti-spam filters to keep unwanted messages out of their subscribers\u2019 inboxes, these products don\u2019t catch every piece of spam received, says Jacinta Tobin, vice president of business development with Cloudmark. Therefore, because ISPs are under obligation to store their subscribers\u2019 e-mail messages for a set amount of time, they end up storing quite a bit of spam, which eats into expensive storage space and complicates maintenance, she says.Cloudmark says it has reviewed the mail stores of numerous ISPs and found that, on average, more than 50 % of the messages stored are spam that wasn\u2019t caught by the ISP\u2019s filters.StorageScan rescans an ISP\u2019s mail store and deletes all known spam, Tobin says, freeing up to 25% of an ISP\u2019s storage capacity. Cloudmark claims its spam-blocking technology is 98 % effective with a near-zero false-positive rate -- the number of messages wrongly classified as spam.The reason Cloudmark\u2019s technology can catch spam messages that other products miss is because of its Collaborative Security Network, made up of a group of e-mail users who regularly report spam, phishing attacks, viruses, and other threats to the company, says Tobin. Based on reports from these users, as well as its own analysis and classification process, Cloudmark updates the spam-blocking rules found in its server software on a regular basis, enabling the software to block a spam blast within as little as three minutes after origination, Tobin says.This network, which officials say includes more than 100 million mailboxes and processes billions of messages everyday, distinguishes Cloudmark\u2019s offering in the crowded anti-spam marketplace, concurs Richi Jennings, lead analyst with Ferris Research\u2019s e-mail security practice.\u201cThe way Cloudmark works is slightly different from the others, they have this distributed reporting network reporting back to Cloudmark central, and they look at this information extremely quickly to develop signatures or hashes of what various bits of spam look like,\u201d Jennings says. The company\u2019s product is updated with signatures often enough that they can catch spam at the mail server level that slipped through spam filters at the gateway level, he adds.Pricing for Storage Scan, available now, depends on the number of mailboxes and amount of mail stored, company officials say.