Zimbra Inc, which had its coming out party at last year’s Web 2.0 conference, claims that it has penetrated roughly 4% of the Microsoft Outlook client market. In raw numbers, that amounts to 1000 paid enterprise customers representing 4 million seats.
Those numbers obviously don’t count the portion of the market that has adopted the free open source version.
Zimbra provides an open source email server that can plug into existing mail clients like Outlook or Notes. It’s best known for its use of Ajax clients that mash together email and the web.
On the back end is a server that uses the Linux file system for storage and the Apache webserver for caching, which it claims is more scalable than Microsoft Exchange. And it uses the MySQL database as a metadata store to make mail more searchable.
Over the past year, the product has come out in two versions, beginning with the first production version in February. The most recent release in August added a WYSIWYG document Wiki editor and some mobile clients.