Microsoft opublikował (w języku angielskim) dokument "Exchange 2010 SP2 Multi-Tenant Scale Guidance" opisujący limity jakie mogą dotyczyć skalowania organizacji wykorzystujących address book policy.
This document contains high-level guidance for properly scaling and deploying a multi-tenant Microsoft Exchange Server 2010 Service Pack 2 solution. It includes details of testing performed in Microsoft labs to validate the scalability of the product and suggests methods that can be used during the design and deployment process to mitigate potential risks associated with such solutions.
Exchange 2010 SP2 Multi-Tenant Scale Guidance