Understanding IRM in Exchange 2010 Hybrid Deployments

Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

Topic Last Modified: 2012-05-18

Information Rights Management (IRM) helps you to protect against leakage of sensitive information by providing persistent online and offline protection of e-mail messages and attachments. Both Exchange 2010, in your on-premises organization, and Exchange Online, in Office 365 for enterprises, support IRM. However, there are differences between the two implementations, and you must configure IRM in the Exchange Online organization before users in that organization can use it.

IRM uses Active Directory Rights Management Services (AD RMS), which is a component of Windows Server 2008 R2. AD RMS allows users to create rights-protected content, such as e-mail messages and attachments, and then control how that content is used, and to whom it’s distributed. Users can specify templates that determine how content can be used. For example, a user may specify that an e-mail message can't be forwarded to other recipients or that information in the message can't be copied.

Learn more about IRM in Exchange 2010 at: Understanding Information Rights Management

Learn more about AD RMS at: Active Directory Rights Management Services Overview

Learn more about configuring IRM at: Configure IRM in Exchange 2010 Hybrid Deployments

IRM in Hybrid Deployments

Exchange uses AD RMS servers in the Active Directory forest in which the Exchange server is installed. For your on-premises Exchange 2010 servers, the on-premises AD RMS server is used. For your Exchange Online organization, AD RMS servers that are maintained within the Microsoft Office 365 datacenters are used. The AD RMS configuration that each Exchange organization uses is independent of any other AD RMS deployment.

AD RMS configuration, and therefore IRM configuration, isn't automatically replicated between your on-premises Exchange organization and the Exchange Online organization. Any AD RMS templates that you've defined aren't automatically copied to the Exchange Online organization. If you want the same AD RMS templates to be available in the Exchange Online organization, you must manually export the templates from your on-premises organization and apply them to the cloud-based organization. See the IRM Configuration in Hybrid Deployments section later in this topic.

User Experience

The IRM configuration that's applied to a user depends on the client the user uses and the location of the user's mailbox. The following table shows the AD RMS server a user will use.

Active AD RMS server

Client	On-premises mailbox	Cloud-based mailbox
Outlook 2007 or Outlook 2010	On-premises AD RMS	On-premises AD RMS
Outlook Web App	On-premises AD RMS	Exchange Online AD RMS
ActiveSync device	On-premises AD RMS	Exchange Online AD RMS

It's possible that, depending on the AD RMS configuration you configure in your on-premises and Exchange Online organizations, a user who uses Outlook 2007 and Outlook Web App may see different AD RMS templates. For this reason, we strongly recommend that you apply the same templates to both your on-premises and Exchange Online organizations.

There should be no difference in the IRM experience for Outlook client users, regardless of whether their mailbox is located in the on-premises or Exchange Online organization.

An Outlook Web App user whose mailbox is located on an Exchange 2010 server can only open rights-protected messages after installing the Rights Management for Internet Explorer add-in. They can't reply to or create new rights-protected messages.

An Outlook Web App user whose mailbox is located in Exchange Online can open rights-protected messages without any additional software and can reply to, and create, new rights-protected messages.

Server Functionality

On-premises Exchange 2010 servers use the AD RMS pre-licensing agent to decrypt rights-protected messages so that users don't need to supply credentials when they open those messages. The on-premises Exchange 2010 server contacts the on-premises AD RMS server to check usage policies and rights, and to request authorization to decrypt the message.

The Exchange Online organization provides several additional IRM-related features that make use of Exchange Online AD RMS. These features, such as journal report decryption, make the content of right-protected messages available to Exchange services for additional processing. For example, the decrypted contents of a journaled message can be saved, along with the original rights-protected message, to allow for easier discovery. Additionally, IRM templates can automatically be applied to messages using either Outlook protection rules or transport rules to ensure that messages adhere to organization policies regarding information protection.

IRM Configuration in Hybrid Deployments

IRM in Exchange relies on AD RMS being deployed in the Active Directory forest in which the Exchange server resides. AD RMS configuration isn't automatically synchronized between the on-premises and Exchange Online organizations. You must manually export the AD RMS configuration, known as a trusted publishing domain (TPD), from your on-premises AD RMS server, and import that configuration into the Exchange Online organization. The TPD contains the AD RMS configuration, including templates, which the Exchange Online organization needs to use IRM.

Learn more at: AD RMS Trusted Publishing Domain Considerations

In addition to applying your on-premises AD RMS configuration to the Exchange Online organization, you must ensure that your AD RMS servers can be contacted by Outlook and ActiveSync clients outside of your on-premises network. You must do this if you want these clients to access rights-protected messages outside of your on-premises network.

After you've configured your on-premises network and exported the TPD data, you need to configure the Exchange Online organization by importing the TPD data and enabling IRM.

Note:
Any time you modify your on-premises AD RMS configuration, you must manually apply the new configuration in the Exchange Online organization. To do so, export the TPD data from your on-premises AD RMS server and import it into the Exchange Online organization.

Learn more at: Configure IRM in Exchange 2010 Hybrid Deployments