VMware is to buy the Zimbra email unit from Yahoo by the end of the first quarter of 2010.

The web-based email and calendar systems manufacturer was bought by Yahoo for $350 million in October 2007 as part of an acquisition drive that preceded the arrival of current CEO Carol Bartz.

Zimbra manages more than 55 million email boxes for businesses, universities and internet service providers. Financial terms of the deal have not been disclosed, but the acquisition opens a new product line opportunity for VMware.

Yahoo will retain the right to draw upon Zimbra's technology to run its own web-based email service.

Nirav Mehta, senior manager at RSA, said that the move was ‘a big step towards delivering IT as a service'.

He said: “So what implications does this have on security? RSA believes that virtualisation provides a clean slate to ‘get security right'. Upwards vertical integration of the VMware stack will extend the benefits of innovative security embedded in the virtualisation layer to cloud-ready applications that are optimised for the stack.

“For example, imagine creation of a new Zimbra email account that in turn triggers the provisioning of virtual machines, security controls and multi-tenancy controls in the vSphere and vCloud platforms.

“In general, the real promise of the VMware acquisition of Zimbra will be unleashed as VMware systematically integrates its core services that enable availability, security, chargeback and multi-tenancy to the SpringSource and Zimbra assets. These are exciting times at VMware and for those of us lucky enough to witness and shape the new IT.”