Often when the Exchange server manages multiple independent companies (multi-tenant) or when divisions of the same large company are managed, it is necessary to isolate the GALs, i.e. Global Adress Book, because this contains the list of all addresses in the domain.
The following procedure allows you to disable its display.
Log in to the Exchange 2010 server with Domain Administrator rights
Use as a "configuration" connection point
Navigate to "CN = All Global Address Lists, CN = Address Lists Container, CN = First Organization, CN = Microsoft Exchange, CN = Services, CN = Configuration, DC = acs-hosting, DC = local"
Disable read capability for everyone or authenticated users.
In this way no user will be able to access the GAL but will be able to use its address books
Here are some screeenshots: