I have the Issue when running get-mailbox from EMS. Can not see all mailboxes even the mailboxes on the Exchange 2010
So, the resolution is to run this command the below and it works, but in a little while the scope changes and again I have to run this command to change the scope for entire forest. Is there a way to set it permanetly so it doensn't change any more.
Set-AdServerSettings -ViewEntireForest $true -PreferredGlobalCatalog