Andy Armagost, systems administrator at Brigham Oil & Gas, in Texas, is also conflicted about the deal, which he believes would have given his company pause for reflection when deciding for Zimbra, but the suite is partially rolled out already at Brigham.
While he shares many of his peers' concerns, he also sees a silver lining: that Zimbra will become more financially secure and able to access Yahoo resources. "I hope this deal works out well for all of us," he said.
Those interviewed generally believe that the best-case scenario would be for Yahoo to interfere as little as possible with the Zimbra team and technology while providing a strong backup.
Satish Dharmaraj, Zimbra's co-founder and CEO, understands that acquisitions often worry customers but said the concerns are unwarranted in this case.
"I already know my budget for the next 5 years, in which there is a continued commitment to growing this business," Dharmaraj said in an interview with IDG News Service.
For starters, Yahoo will not dismantle Zimbra to boost Yahoo Mail. "If Yahoo wanted the people and the technology to bolster the Yahoo consumer mail group, $350 million is a lot to pay," Dharmaraj said.
"We're going to be kept whole as a business unit and we'll execute on our current strategy," he added.
Likewise, it's illogical to think Yahoo will rip out its Yahoo Mail infrastructure, which supports about 250 million consumers, and swap in the Zimbra technology, designed mostly for businesses. "Those are paranoid fears," Dharmaraj said.
Zimbra's team will help refine and improve portions of Yahoo Mail, on a case-by-case basis. Currently, the only component slated for a Zimbra revamping is Yahoo Calendar, he said.
Meanwhile, the downloadable, server-based versions of Zimbra's suite aren't going away, so those customers can rest easy, including those who have signed 5-year agreements, he said.
Specifically, Zimbra will maintain the same commitment for the open-source version of this downloadable suite, keeping its development on par with the commercial "Network" version.
Zimbra, founded in 2003, has an installed base of about 9 million mailboxes in over 100,000 organizations, although it deals directly with about 1,300 customers and channel partners, he said. Customers include Comcast Corp. and New York University.
Its core strength is e-mail, and it has commonly been considered an alternative to Exchange, but the suite also includes a word processor and a spreadsheet application. These let users create, share and collaboratively edit documents.
With e-mail, calendar, contacts list and office applications, it also competes against PC-based suites such as Microsoft Office and Web-hosted suites such as Google Apps.
Dharmaraj said Zimbra will sell the suite directly as a hosted service, something for which it had previously relied on hosting partners. As with direct sales of the downloadable versions, Zimbra will sell the hosted suite at a premium over the prices it gives to hosting partners.
Also unfounded are fears that Yahoo will force Zimbra to limit its compatibility with Yahoo competitors, he said. Yahoo realizes that a big draw of the Zimbra suite is precisely its open platform, which lets external developers create application mashups called "zimlets."
The deal gives Zimbra a financial and resources boost, as well as heightened brand credibility with potential enterprise customers that as a 100-employee startup it didn't have, he said.
If anything, Zimbra will be able to step up its development efforts. Version 5.0 of the Zimbra Collaboration Suite is due in December, and version 5.5 and beyond will follow, he said.
Finally, he said he and the other members of the Zimbra executive team are committed for the long haul. "Zimbra is our baby," he said. "The reason we made this deal is to grow Zimbra."
Yahoo's Brad Garlinghouse, senior vice president of communications and communities, reiterated Dharmaraj's commitments and challenges the perception that Yahoo only knows how to support consumers.
For example, Yahoo provides Web hosting and domain registration-related services to hundreds of thousands of companies, while its advertising business includes a vast network of marketers and publishers, he said.
Moreover, it has long-standing partnerships with carriers such as AT&T and British Telecom, he added. "Those are very large commitments we have made in our systems that aren't consumer-facing," Garlinghouse said in an interview.
Regarding Yahoo's ability to support enterprise customers, he points towards the know-how involved in providing reliable performance at a massive scale for services such as Yahoo Mail. "This is a natural extension of what we're incredibly good at with a company, in Zimbra, that also is best-of-breed. We bring the best of both worlds together," Garlinghouse said.
Assurances and promises are all good, but concerned customers said the antidote to their misgivings will be concrete actions. "I have no interest in asking simple questions and listening to Yahoo's spin. Only time can answer any question I have," Other World's Phillips said.