Cloudmark updates its e-mail filtering software "Cloudmark DesktopOne (formerly Cloudmark Desktop)" for Outlook, Outlook Express, Thunderbird 3, Windows Mail, and Windows Live Mail. Free DesktopOne limits the number of inboxes monitored to just one IMAP, POP, or webmail account at a time, and gives users just one Spam folder, but does so with no time limit. The inbox being protected by the software can be changed at any time as well. The software still works on its "Fingerprint" system, which's essentially a database of untrustworthy senders, updated every time a user marks an e-mail message as spam or phishing.
To open monitoring to an unlimited number of inboxes, and add premium features, Cloudmark has a Pro subscription tier for $19.99 per year.
More Info: DesktopOne