The Messaging Gateway for Service Providers (SMG-SP) Implementation Guide refers to the Brightmail Reputation Service (BRS) on page 55 as a downloadable reputation service option. This section was included in the implementation guide in error and the BRS has been deprecated in favor of the integration of a DNS reputation service lookup for both safe sender and bad sender lists. New accounts for the BRS are no longer being provisioned.
Please see page 59 of the SMG-SP Implementation Guide or TECH230734 for instructions on configuring DNS reputation services in SMG-SP.