Yahoo on Tuesday became the latest entrant into the cloud computing market as its subsidiary Zimbra said schools will be able to access its open-source messaging and collaboration services on the Internet.

Sunnyvale, California-based Zimbra, which Yahoo acquired just over a year ago, gives Yahoo a stake in cloud computing, often called SaaS, or software as a service.

“Yahoo obviously saw Zimbra as a good SaaS entry point, and collaboration is far and away the highest demand SaaS solution,” said Mark Koenig, vice president of research at Saugatuck Technology.

Yahoo joins IBM, Google, Amazon, Sun, Cisco, Microsoft, and hundreds of smaller companies that are offering services without the management headaches of installed hardware and software.

“These companies have learned that if you own the email address you lock the user in to a series of other services,” Mr. Koenig said.

Four-year-old Zimbra will use Yahoo’s massive data centers for the first time to offer its organizational messaging and collaboration technology as cloud services under the Yahoo brand.

Zimbra offers its collaboration technology through 400 cloud computing partners either under the Zimbra brand or the partners’ brands, but the new Yahoo-branded service will be its first direct cloud offering.

“When we were acquired by Yahoo a year ago we felt that Yahoo would provide us with the opportunity to get a SaaS solution into the market quickly using Yahoo’s data centers as leverage,” said John Robb, Zimbra’s vice president of marketing and product management.

More than 500 educational institutions currently use Zimbra’s messaging and collaboration technology and they will now have the option of switching all or part of their groupware applications to the cloud.