I have configured each my proxy to use integrated Authentication. Now the outlook can't access hotmail server. Here is the error: Task 'Hotmail: Folder:Inbox Synchronizing headers.' reported error (0x800CCC37) : 'Your proxy requires you to authenticate. Contact your network administrator for assistance.The server responded 'Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy service is denied. )'. '