Use the Permissions property page to specify the rights that users or groups have on the CA object. You delegate permissions to a user or group by assigning them a role. Roles are sets of rights that define how much and what type of access a user or group has on an object. For the CA object, Microsoft Exchange Server provides Admin, Permissions Admin, and User default roles. You can also create custom roles.
For more information on permissions, see Microsoft Exchange Server Getting Started.