<A target="_blank" href="http://www.zdnet.com/blog/microsoft/microsoft-investigating-windows-phone-users-office-365-exchange-2003-access-issues/10972">People who have applied the Mango WinPhone update are complaining of problems</A> accessing Office 365 and Exchange 2003. Currently, Microsoft is investigating. One solution is to upgrade to Exchange 2007 or 2010.