This post describes Hosted Messaging and Collaboration (HMC) and Active Directory Visibility mode, how they’re different, how to enable (and disable) one or the other and what you can do with them in your environments.

Microsoft’s Solution for Hosted Messaging and Collaboration (HMC) is a multitenant environment, that Microsoft partners can use to offer Microsoft Exchange, Microsoft Sharepoint and Microsoft Office Communications Server (OCS) to customers from within a datacenter. The current version is HMC 4.5, offering Exchange 2007 with Service Pack 1, Sharepoint Services 3.0 with Service Pack 1 and Office Communications Server (OCS) 2007.

Hosted Messaging and Collaboration (HMC) can be seen as the partner option to Business Processes Online Services (BPOS), in which Microsoft offers customers access to Exchange Server, Sharepoint Services, Live Meeting Server and (soon) Office Communications Server.

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