At first glance, Yahoo is  struggling on multiple fronts. But take a closer look and you may discover that Zimbra — the open source email system Yahoo acquired in September 2007 — is thriving under Yahoo’s ownership. Skeptical? Consider the continued growth of Zimbra’s channel partner program.

Indeed, Zimbra generated roughly 52 percent of its revenue from VARs, hosting partners and other solutions providers in 2008, up from 34 percent in 2007, according to The VAR Guy’s Open Source 50 report. Plus, Zimbra’s partner network grew to 665 companies in 2008, up 40 percent from 475 partners in 2007, The VAR Guy’s research shows.

Overall, Zimbra says more than 30,000 organizations are leveraging 20 million Zimbra email and collaboration inboxes. The company’s latest market sweet spot appears to be colleges, where Zimbra Hosted for EDU has carved out a niche for itself. Eager adopters include Kansas State University, according to CNet.

So, is Zimbra really thriving under Yahoo? Are the stats above too good to be true? The VAR Guy believes his research is rock-solid. But he realizes it’s difficult (er, impossible) to determine Zimbra’s financial momentum since Yahoo doesn’t offer up those stats. Plus, many of those 30 million Zimbra inboxes could be of the free variety.

Still, Zimbra appears to be growing its channel partner program pretty rapidly.

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