Yahoo is selling the email service Zimbra to VMware as part of an effort to focus on the Internet services that generate most of its revenue.
Financial terms of the deal announced Tuesday weren't disclosed.
Zimbra manages more than 55 million email boxes for businesses, universities and Internet service providers.
The acquisition opens a new product line for VMware, which sells software that enables a single computer to function like multiple machines.
Yahoo is retaining the right to draw upon Zimbra's technology to run its own Web-based email service.
The sale is expected to close by the end of March.