Vendors continue to improve antispam products and introduce new ones. Two you should know about are MailFrontier's Matador and Tumbleweed Communications' Dynamic Anti-Spam Service.Matador is a desktop antispam product introduced in November. The product integrates into Microsoft Outlook and uses multiple techniques to fight spam, including dynamic whitelisting, which collects a user's e-mail conversation history and puts this information into a whitelist; personal and global blacklisting; content filtering based on statistical analysis of incoming e-mail; and collaborative spam identification, in which users are asked to identify spam. Matador also performs a challenge to new senders.The beta version of Matador 2.0 has been released and adds support for Outlook Express, IMAP, Hotmail and MSN. Matador sells for $29.95 per seat initially and $8.95 per year for updates.MailFrontier also announced its Anti-Spam Gateway (ASG), which is designed for enterprises. The ASG can work with or without Matador at the desktop level and is designed to require very little maintenance. MailFrontier will automatically update the gateway software very frequently with new spam signature data. The ASG works with a wide variety of messaging servers and is priced at about $8 to $15 per seat.Tumbleweed unveiled its Dynamic Anti-Spam Service, which will work with the company's Secure Mail 5.5, an e-mail policy gateway that provides regulatory compliance, policy enforcement, virus detection, content scanning and other capabilities.The subscription-based service will automatically update the spam analysis engine contained in Secure Mail with spam signatures created by Tumbleweed's newly established Message Protection Lab. The spam analysis engine uses statistical and heuristic analysis to identify spam, as well as whitelists, blacklists, address validation, behavior analysis and other techniques. Tumbleweed claims it can capture 90% of spam with a very low false-positive ratio. Tumbleweed's approach is to integrate spam filtering with other types of content filtering and policy management into a single solution for e-mail management.