Understanding Shared Free/Busy


Applies to: Exchange Server 2010 SP2, Exchange Server 2010 SP1

Topic Last Modified: 2011-07-25

Sharing free/busy (calendar availability) information between users located on-premises and in the cloud-based organization is one of the primary benefits of a hybrid deployment. Users in both organizations can view each other's calendars just as if they were located in the same physical organization. This makes scheduling meetings and resources easy and efficient.

Several components in a hybrid deployment are required to enable the shared free/busy feature:

  • Federation trust   Both the on-premises and cloud-based organization need to have a federation trust established with the Microsoft Federation Gateway. A federation trust is a one-to-one relationship with the Microsoft Federation Gateway that defines parameters for your Exchange organization. The gateway uses these parameters when acting as a trust broker between your on-premises and cloud-based organization to exchange free/busy information between organization users. By default, a federation trust with the gateway is automatically configured for your cloud-based organization when the account is created.

    Learn more at: Understanding Federated Delegation

  • Organization relationships   Organization relationships need to be configured for both the on-premises and cloud-based organization. An organization relationship defines the level of free/busy information shared for an organization.

    Learn more at: Create an Organization Relationship

When configuring your organization for a hybrid deployment, configuring shared free/busy calendar access isn't a requirement in all scenarios. However, creating a federation trust with the Microsoft Federation Gateway and configuring an organization relationship for the on-premises and cloud-based organization are hybrid deployment requirements. If you don't want to allow free/busy sharing between your organization users, you can configure the organization relationship access level accordingly.

The hybrid deployment features shown in the following table have a dependency on federation trusts and organization relationships.


Messaging area Features

E-mail client

  • Message tracking

  • MailTips

  • Multi-mailbox search


  • Mailbox moves

  • Secure intra-organization message delivery

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