Cloudmark Desktop 5.3.3 for Microsoft Outlook Review

Rated: 4.5 / 5

Cloudmark pioneered the concept of community-based spam filtering, and its community is now over a million strong. Cloudmark Desktop 5.3.3 for Microsoft Outlook keeps most spam out of your Outlook inbox while marking virtually no valid mail as spam—and that's what I look for in a spam filter. Separate versions of the program support Outlook Express and Thunderbird, and a version for Vista's Windows Mail is in the works.

Where many antispam products filter only standard POP3 e-mail, Cloudmark Desktop strips out spam from any e-mail account that your e-mail client supports. That includes POP3 and IMAP accounts, webmail accounts accessed via POP3, and (for Outlook only) Exchange-based mail accounts. About the only kind of e-mail it can't filter is a Web-based account that doesn't offer POP3 access.

Community Intelligence

Spammers spew their useless or harmful messages to millions of victims, and that fact is part of what makes community-based filtering work. When any community member marks a message as spam, Cloudmark Desktop boils down the message content to a unique fingerprint and sends that fingerprint to a central database. If the database receives enough reports for the exact same message (based on the fingerprint), it concludes that the message really is spam and blocks it for all other members.

If it were as simple as that, a determined spammer could undermine the system by joining the community and marking messages as not spam. To keep people from gaming the system, Cloudmark maintains a trust rating for every user. If the community as a whole agrees that a message you've blocked is spam, your trust rating goes up just a bit. If the community doesn't agree with your assessment, your trust goes down. The higher your trust rating, the more weight your opinion carries.

You can add specific domains or addresses to a whitelist and also automatically whitelist any address that's in your Contacts list. Mail from whitelisted addresses will always get through. But I can't think of a situation where this would be necessary. In order to get misfiled as spam, the identical message would have to be reported as spam by multiple community members. Thus Cloudmark should never identify a unique message from an individual as spam. Most users can ignore the whitelist and leave the other settings at their default values.

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