"If VMware 'gets' that Zimbra is the tail which will wag the VMware dog as VMware tries to penetrate the IaaS [infrastructure as a service] and SaaS markets, then Zimbra's best days are still ahead of it," Stone said. "If VMware conducts itself with the hubris unfortunately all too common with buyers, then this deal will fail, just like too many other acquisitions."

Bill Pray, an analyst at Burton Group, notes that VMware has been a popular choice for virtualizing e-mail servers, so being able to market its own e-mail system for on-premise deployments will make sense. Zimbra also stands to gain.

"For Zimbra, getting out from under the Yahoo umbrella and going to a parent company that can execute on an enterprise strategy with them will definitely be a bonus," Pray said.

In addition, Zimbra gives VMware another tool to sell, said Rebecca Wettemann, a Nucleus Research analyst. "VMware is selling to the same person who decides what calendars and mailboxes applications the organization uses. VMware is firmly in the IT decision-maker box," she said.

Yahoo benefitted from integrating some Zimbra technology into Yahoo Mail and Yahoo Calendar, but Zimbra never became a core service and as such wasn't a strategic fit for Yahoo, whose revenue comes mostly from advertising in its consumer online services.