Yahoo's Zimbra Desktop is a strange beast. Chiefly intended for pre-existing users of Zimbra's business services, or those who access Zimbra's hosted server through the open-source community, the offline, multiplatform, open source Zimbra Desktop also has some intriguing uses for the rest of us. However, many features are acutely in beta. This makes its position as a standalone app precarious, as it does this review--pre-existing Zimbra fellows get a much richer feature set added to what is their chief e-mail in-box. For them, the emphasis on collaborating wiki documents, uploading files, and sharing entire subsets of the in-box--like address books and message folders--gives the application its value. Those outside the server's glow will find a half-enabled app still nibbled by bugs.
Most will want to try Zimbra Desktop for its capability to manage multiple e-mail accounts from its single in-box. It will sync contacts and calendars from Yahoo Mail and Gmail, though a syncing dilemma with Gmail currently restricts the buddy list to those you've added by hand. Likewise, Gmail's labels won't synchronize with Zimbra tags in this build. Hotmail is another Web mail service supported with caveats. It only works for those with premium Plus accounts, or those who have been grandfathered in from the Outlook Express days. Other IMAP and POP services are eligible for Zimbra's in-box panoply.
The e-mail accounts that do make it into Zimbra without a hitch are treated with an overarching search bar, the ability to tag messages, and a feature that clusters conversations with the same subject line. Unlike Gmail, Zimbra Desktop won't thread conversations into one e-mail entry, but it will list previous conversations with the same subject line beneath the latest message.
Also open to everyone are Zimbra Desktop's extremely simple wiki documents, which you can create, but can't easily share with others if you don't engage Zimbra's server. In previous tests, stability became an issue when running a spreadsheet and minimized applications. While the portrait isn't exactly rosy, the adventurous can still benefit from the multi in-box management tools, as Zimbra broadens its appeal and its promise to non-Zimbra Server users.