This was a question from a university in Utah looking to deploy students on Office 365 and keep their faculty staff with on prem Exchange 2010.

What does Exchange Hybrid deployment mean?

Exchange Hybrid deployment means you want to maintain rich coexistence with Exchange Online and an Exchange on premises installation.

What versions of Exchange server support Hybrid deployment?

Exchange 2010, Exchange 2007, Exchange 2003.

What functionality do you get with Exchange Hybrid deployment?

When you configure Exchange Hybrid mode you enable the following rich coexistence:

  • Mail routing between on-premises and cloud-based Exchange organizations
  • Mail routing with a shared domain namespace. For example, both on-premises and cloud-based organizations use the @contoso.edu SMTP domain.
  • A unified global address list, also called a “shared address book”
  • Free/busy and calendar sharing between on-premises and cloud-based Exchange organizations

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  • Centralized control of mail flow. The on-premises organization can control mail flow for the on-premises and cloud-based organizations.
  • A single Outlook Web App URL for both the on-premises and cloud-based Exchange organizations
  • The ability to move existing on-premises mailboxes to the cloud-based organization or offboard back to on prem

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  • Centralized mailbox management using the on-premises Exchange Management Console (EMC)

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  • Message tracking, MailTips, and multi-mailbox search between on-premises and cloud-based organizations

What infrastructure do I need to enable Exchange hybrid deployment?

We require an Exchange 2010 CAS Sp1 server to be installed on prem to enable a hybrid deployment. This will also require an extension of the Active Directory schema during the installation of Exchange 2010. Additionally, we require a DirSync server to be installed to maintain a synchronized address book between on prem and the cloud. 

Here is a diagram depicting a customer with Exchange 2007 on prem and wanting a Hybrid deployment in addition to single sign on:

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Do I need to purchase a license for the Exchange 2010 hybrid server on prem?

No, if you have a production tenant for Exchange Online you can request a hybrid server product key via Online Support to license the hybrid server. Read more here.

Where can I find more details about hybrid deployment?

See my previous blog post here for some useful links on step by step information on hybrid deployments.