What is Hybrid | A Hybrid Office 365 Migration

Enclyne has been working with Microsoft Cloud Services for over 11 years. We’ve been answering questions like “What is hybrid?”, “What is a hybrid Microsoft 365 migration?”, and “What are the advantages of Exchange Hybrid?” for quite some time now. We’d like to answer some of those questions here.

What is hybrid?

In the IT world, “hybrid” generally refers to the configuration of two or more otherwise disparate technologies to create a single, unified solution. In the case of Microsoft 365, an organization can integrate cloud services like SharePoint Online, Microsoft Teams, and Exchange Online with their on-premises counterparts to create officially supported “Microsoft Hybrid” solutions (note the formalized capital H).

Active Directory Domain Services, Exchange Server, and Outlook client have been the bread and butter of Microsoft’s business productivity suite for two decades. Because of this, the first step for most Office 365 onboarding projects is migrating identities and mail. when one refers to “hybrid migration”, they are referring to a specific, by-the-book deployment of Exchange Hybrid. When deployed correctly, Exchange Hybrid provides a path for migrating mail objects to Office 365 with zero downtime and the least user impact of all migration options.

Your Migration Options

When it comes to an Exchange on-premises to Exchange Online email migration, you have a few options, but one is far superior to the others.

For organizations that can weather long-term migrations to the cloud, Microsoft offers their own guide for both staged and cutover migrations. Be wary! These approaches are not for the faint of heart. They often require significant downtime, flexible timelines, and patience.

For most organizations, a staged or cutover migration strategy using third-party tools is often chosen. With third-party tools the entire planning stage is more defined. Timelines are more predictable, testing is easier, and most products come with support if you run into issues. When planned by a migration specialist, third-party tools can also offer the fastest turnaround. One major drawback to this approach is the requirement for new Outlook profiles to be created. A second drawback is often expense.

The best option by far is an Exchange Hybrid migration. While initial deployment is more complex than the other migration options, the benefits tend to outweigh the disadvantages come migration day. Hybrid deployments offer the most robust coexistence experience between mailboxes residing on premises and those that have already been migrated (see below). New Outlook profiles are not required post-migration, and often upgraded server licensing is completely free. While Hybrid Exchange is not always a viable option, we suggest it whenever possible. If done correctly, users will not even know they’ve been part of a migration and you’ll save a buck or two.

Coexistence Explained

The term “coexistence” refers to the number of features and collaboration options available between users who reside in two independent environments during migration. The collaboration features available during the migration process depends entirely upon the migration strategy chosen and only become relevant after the first mailbox has been migrated. Coexistence is irrelevant in cutover migrations, as everyone is transitioned at once.

Exchange Hybrid migrations offer what is known officially as “rich coexistence”, which makes available Exchange features like address books, calendar free/busy sharing, delegate access permissions, and automatic Outlook profile management. There are also limited options for hybrid Public Folder access as well. Rich coexistence is the highest level of coexistence.

In contrast, staged migrations offer “simple coexistence”, the features of which are limited to mail flow and forwarding between the environments. Simple coexistence allows for uninterrupted mail flow during a staged migration process, but address books and free/busy information will not be available cross-premises. Special consideration must also be taken with Resource Mailboxes, and Distribution Groups.

Extending Coexistence After Your Email Migration

Unlike all other migration strategies, Microsoft’s vision for Exchange Hybrid was to be deployed as a long-term solution. While some organizations choose to decommission their on-premises Exchange Hybrid servers after migration, the design and intent from Microsoft’s perspective is to keep at least one Hybrid management server on premises indefinitely. Cloud-based objects can be created and managed via familiar tools like Exchange Management Console or Exchange Management Shell while hybrid is in place. The hybrid server would also provide an ongoing rich coexistence environment for the incorporation of local smart hosts or onboarding of newly-acquired Exchange organizations.

Despite the above benefits, many admins opt to decommission Hybrid Exchange after migration. Even if the official decommissioning procedure is followed, this results in a non-supported Exchange scenario. Nevertheless, removing Exchange while leaving AD Connect intact is a common scenario that we have confidently implemented for many customers.

Exchange Hybrid Requirements

Exchange Hybrid can only be configured in Exchange 2010, 2013, 2016 and 2019 environments. Exchange 2007 can be migrated via Hybrid, but a 2010 server must be deployed first. A single server in the environment will perform the Hybrid role, but it’s recommended that all servers be brought up to date with the latest Cumulative Updates prior to deployment. Typically firewall rules will have to be modified to allow traffic directly from the Exchange Online Protection servers. Often SSL Certificates must be updated to include certain entries. Finally, Azure AD Connect is a requirement as well. The installation of AD Connect often requires basic OS updates that may in turn require planned reboot.

In addition to the above basic prerequisites, our talented engineers engage in extensive discovery, reporting, planning, remediation, and testing procedures throughout the Hybrid deployment phase. This ensures that there are no surprises for your team and that your end users are handled with care during each phase of the project.

Working with a Hybrid Partner

Organizations who have successfully onboarded Office 365 using Exchange Hybrid know how complex initial configuration can be, especially when mailboxes aren’t the only concern. Adding to the complexity is the fact that patches and improvements to the rich coexistence experience are released almost daily, resulting in regular changes to the process. Hybrid Exchange is the most complex basic mail server deployment scenario ever designed, but successful implementation pays off big in the end. Working with an experienced partner who understands the ins and outs of Office 365 Hybrid licensing, deployment, troubleshooting, and management can be the key to unlocking a smooth transition to the cloud, and we would love to partner with you.

More questions? Want more migration tips like the one above?

Contact us for your free email migration consultation! We’d love to dive further into your ‘what is hybrid’ question and discuss your current email environment and present you with the migration options that are best fit for your organization!