New-MailboxFolder doesn’t have the capability of creating folders in users mailboxes.
When administrator is logged in . It has the capability of creating a folder only in Administrator mailbox
So an administrator cannot create Custom root folders in users mailboxes using this command. (RBAC has Implicit read scope set to Self – Which cannot be overridden)
EWS Managed API is the only alternative available to accomplish these tasks
To Create Folder in Administrator Mailbox
New-MailboxFolder -Parent administrator -Name Folder1
To Create Folder in Administrator Mailbox Below Inbox Folder
New-MailboxFolder -Parent :\Inbox -Name Folder1
Trying to Create a mailbox folder in user mailbox called “RR”
You will endup with an Error –saying it Doesn’t exist as it doesn’t have read permissions over the other objects
New-MailboxFolder -Parent RR -Name Folder1
The specified mailbox “RR” doesn’t exist.
+ CategoryInfo : NotSpecified: (:) [New-MailboxFolder], ManagementObjectNotFoundException
+ FullyQualifiedErrorId : [Server=EXCH2013,RequestId=4ccd32aa-dd39-489d-918b-5b37c8ac8ee8,TimeStamp=7/21/2014 5:15
:21 AM] [FailureCategory=Cmdlet-ManagementObjectNotFoundException] DC37182,Microsoft.Exchange.Management.StoreTask
+ PSComputerName : exch2013.testcareexchange.biz