i get the following error when running add-federateddomain. Unable to reserve the URI "mydomain.com" for the domain "mydomain.com" on application identifier "000000001234568". Det ailed information: "An error occurred accessing Windows Live. Detailed information: "Unexpected Internal Error".". + CategoryInfo : InvalidResult: (:) [Add-FederatedDomain], UnableToReserveUriException + FullyQualifiedErrorId : 81C3F868,Microsoft.Exchange.Management.SystemConfigurationTasks.AddFederatedDomainDan

Hi, Please verify if mydomain.com is the accept domain in the exchange orginization. Please verify if this mydomain.com has been registered for SSO. You can try to use Get-FederatedOrganizationIdentifier to verify the settings Manage Federation http://technet.microsoft.com/en-us/library/dd876922.aspxXiu Zhang TechNet Community Support