how to disable for OU's admin to add/delete/change e-mail addresses and set a quota on mailbox?

Hi, You need to set deny permission on those attributes for OU Admins with Add-AdPermissions. Code SnippetAdd-AdPermissions ...... -Deny:$true Refer split permissions model reference to find the related attributes which you want to disable. Split Permissions Model Referencehttp://technet.microsoft.com/en-us/library/bb430782(EXCHG.80).aspx Add-ADPermissionhttp://technet.microsoft.com/en-us/library/bb124403(EXCHG.80).aspx

thanks, this is it!