Prevent Mailbox AutoMapping
With Exchange 2010 came the great AutoMapping feature. With it, administrators could grant users full access to mailboxes and these would automatically appear in user’s Outlook without the need to manually add them.
As you might know, this is done by using an Active Directory attribute on the user’s mailbox called msExchDelegateListLink that contains a list of Distinguished Names of mailboxes the user has full access to and should auto-mount in Outlook.
However, in cases where administrators have access to dozens, hundreds or thousands of mailboxes, this is not ideal... You can give permissions and then manually edit msExchDelegateListLink to remove the mailbox from the list or create a script to do this automatically, but with Exchange 2010 SP2 comes an easier way to achieve this.
By using the Add-MailboxPermission cmdlet you now have available the –AutoMapping parameters that allows you to specify if the mailbox should auto-mount or not!
Add-MailboxPermission "mailbox" -User “user” -AccessRights FullAccess –AutoMapping $False