From Interfax China (link):
The main sites of both Hotmail (http://www.hotmail.com) and Windows Live Mail (http://www.live.com) of Microsoft have been widely inaccessible from mainland China as of May 1, 2006. Access to the sites has yet to be restored.
“We have received quite a large amount of complaints from Hotmail users in mainland China,” said a customer service official with Microsoft China when contacted by Interfax Tuesday. The official gave no reason but asked users to report the error at (http://cn.support.msn.com).
Microsoft spokespersons could not be reached for comment.