Getting Started with Hybrid Exchange Deployment

A Hybrid Exchange configuration provides integration between an on-premises Exchange organization and Exchange Online (Office 365), allowing the two organizations to appear as one for end users and administrators.

Hybrid Exchange configurations can be used for two scenarios:

·        As a migration path between on-premises Exchange Server and Office 365

·        As a permanent state for your on-premises Exchange and Office 365 organizations

Compared to other native Office 365 migration methods, a Hybrid Exchange deploymentquite simply provides the best end user experience. Although the trade-off for IT is a more complex infrastructure than a Staged or Cutover migration requires, the pay-off is well worth it, if you ask me.

Listen to Michael Van Horenbeeck and I discussing Hybrid Exchange on the Exchange Server Pro Podcast.

Benefits of Hybrid Exchange Configuration

Here are five benefits of a Hybrid configuration, and how they make migrations and ongoing co-existence with Office 365 better for your entire organization.


A Hybrid configuration requires a synchronized identity model, which involves the deployment of a directory synchronization tool such as Azure AD Connect. You can deploy directory synchronization with password sync for “Same Sign-On”, or directory synchronization with federated identity (AD FS) for “Single Sign-On”. Either way, the sign-on experience is better for users because they don’t need to manage two sets of credentials.

Read more about planning an identity model for Office 365.

Email Hygiene

Exchange Online Protection is provided with all Exchange Online plans, providing secure mail routing between your on-premises Exchange servers and Exchange Online, and also protecting your organization from spam and malware in emails. You can also enable EOP Advanced Threat Protection for additional protection from zero day attacks and malicious links. As a cloud-based service, EOP eliminates the need to operate a third party email security solution while also offloading the burden of receiving and processing all of that spam and malware traffic from your on-premises network.

Rich Co-Existence

In a Hybrid configuration, on-premises Exchange and Exchange Online mailboxes can collaborate as though they are in the same organization. Outlook calendar and free/busy information is available across both environments, along with a common Global Address List and emails between on-premises and cloud recipients being treated as internal messages.

Remote Mailbox Moves

Move requests between Exchange on-premises and Exchange Online work like mailbox migrations between two on-premises databases, occurring online and non-disruptively to end users. After a mailbox has been moved the Outlook profile is automatically updated, and the OST file does not need to be rebuilt, which removes the burden of deskside support and network traffic that occurs in a Cutover or Staged migration.

Cloud on Your Terms

A Hybrid configuration allows for both on-boarding to Exchange Online, and off-boarding back to Exchange on-premises. This allows an organization to move one, or just a few mailboxes to the cloud for a pilot phase. If any problems are encountered, then the mailboxes can simply be moved back to on-premises Exchange servers, an option that is not possible with Cutover and Staged migrations.

Hybrid Exchange Demonstration

Over a series of upcoming articles, I’ll walk through a Hybrid Exchange deployment scenario for an example organization. The Exchange Server Pro organization has a co-existence on-premises environment of Exchange Server 2010, 2013 and 2016, including the use of Edge Transport servers. Using this example organization I’ll demonstrate how to prepare and establish a Hybrid configuration, perform a variety of administration tasks, and how to leverage Office 365 features in a Hybrid environment.