In an Exchange 2007 deployed environment, Outlook 2007 clients can download their Offline Address Book (OAB) via a web-based distribution point published on a Client Access Server (CAS). Hosted Messaging and Collaboration version 4.5 supports this new distribution mechanism, allowing organizations and users to be provisioned and configured to take advantage of the enhanced functionality.

At the service level, web-based OAB distribution can be added as a new plan feature, and offered at a discounted price to incent customers to migrate to Outlook 2007, and help reduce legacy client support for Service Providers.