This post goes over how to grant full access to all public folders for a user in Microsoft Exchange. I recently was migrating all public folders from an Exchange 2010 to Office 365 Environment and didn’t have access to some of the folders. Consequently, this solution saved me a lot of time from doing it through a GUI.
Enter the following in Exchange Management Shell:
Get-PublicFolder –Identity "\Root Folder Name" -Recurse | Add-PublicFolderAdministrativePermission -User "ctitus" -AccessRights AllExtendedRights
This will recurse the root folder and grant all rights to the user you specify.