Your gateway can determine whether to backbone a message to a particular recipient based on the recipient’s address. To implement this feature, you must provide a Microsoft Exchange Server Administrator program property page on the gateway object. The gateway administrator can use this property page to implement an address space table. This table defines a particular range of addresses as belonging to another Microsoft Exchange Server site or to a set of users who all use MAPI-compatible clients. For each Responsibility-TRUE recipient address, the gateway compares the address to its backbone address space table and decides whether that recipient requires backboning.