I wrote an article on this subject in my another Blog. ink as below:http://cloudcompute.info/create-custom-folder-in-exchange-online-mailboxes-using-graph-api-using-windows-powershell/
Lesson: Exchange 2010 SP2 The requested search root domain.local/Users’ is not within the scope of this operation. Cannot perform searches outside the scope ‘child.domain.local’. I