As of September 7th, we are running Zimbra Network Professional Edition version 5.0.9. In most cases 01.com tests both the release and its associated software such as Outlook and iSync connectors prior to installing the latest releases.

This "sandboxing" typically means 01.com is about 30 days behind the release of the most recent version of Zimbra in general release.  Our sandbox is a Zimbra multi-node installation that emulates our production Zimbra cloud hosting environment.  While we recongize a primary value of Zimbra is its rapid pace of development, we are conservative about our upgrades, prioritizing the stability and reliability of the 01.com Zimbra cloud over new features and bug-fixes.

If you'd like to read more about Zimbra 5, and see some screen shots from it, please see our screen shots section here in our public FAQs, or visit our blog.