Examples of such applications include the Google search service, the Hotmail e-mail service, and the Flickr photo-sharing service.

The company responded by immediately shutting down the Hotmail service.

Using stolen passwords, they then used Microsoft's Hotmail service to send snippets of the company's source code to an email address in Russia.

Microsoft said yesterday that it would file a similar suit in Washington State because much of the spam was aimed at its Hotmail e-mail service.

Blue Mountain further expanded when Microsoft promoted its service on its free Hotmail service.

The most embarrassing deactivation of a corporate domain name occurred late last year when Microsoft failed to renew the registration of a domain name critical to its Hotmail e-mail service.

The Hotmail service from Microsoft, with 140 million users, has been a fat target for spammers.

Yesterday, Compaq said it would offer electronic mail on the site using software based on Microsoft's Hotmail service.

Last month Microsoft retooled its Hotmail service, adding a feature that allows users to block Web bugs placed inside e-mail messages.

Yahoo offers four megabytes of storage for free subscribers, Microsoft's free Hotmail service provides two megabytes, while each AOL screen name has a 20-megabyte storage limit.