What to Consider in an Office 365 Hybrid Exchange Deployment

The advantages of cloud solutions like Office 365 are clear. But as an IT admin, you want to maintain administrative control over your email environment. An Office 365 hybrid Exchange deployment combines the best of Exchange and the cloud into one powerhouse solution.

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With Office 365, you gain the seamless look and feel of an on-premises Exchange Server with Exchange Online. A hybrid solution is a great segue to fully migrating to Exchange Online.

Office 365 Hybrid Exchange Deployment FAQs

Why would you use a hybrid deployment?

If you’re considering migrating to Office 365 from an on-premises server, an Office 365 hybrid Exchange deployment can help bridge the gap. Hybrid Exchange deployments are sustainable for over time, so you can gradually migrate to Office 365. This environment allows users with on-premises mailboxes to find others in the Exchange Online global address list. Users can send, receive and reply to emails to other users regardless whether their mailbox is on-premises or online.

What features will you gain in an Office 365 hybrid Exchange deployment?

An Office 365 hybrid Exchange deployment offers several features to secure mail routing between both environments.

Transport Layer Security

The platform authenticates, encrypts and transfers emails sent between recipients in either environment through Transport Layer Security (TLS). TLS disguises the messages so users never notice a change, though their messages are protected.

Free/busy and calendar sharing

is also available between on-premises and Office 365 — and a major benefit of hybrid deployments. Users can share and view one another’s calendars across environments, easing meeting scheduling and sharing resources.

Establishing custom routing of outbound emails between both environments

Office 365 can route outbound messages through your on-premises server or a hosted service. In turn, you gain data loss prevention, post-processing of outgoing emails and a private network to emails partners.

Address Rewrite

A hybrid environment also supports Address Rewrite, which routes outgoing emails through your on-premises server to modify the address. This masks your sub-domains and makes your emails appear to come from a single domain — even if you have a multi-domain environment.

What should you consider about this type of deployment?

Before you take the hybrid route with your business email deployment, there are a few things to consider.

Review the hybrid Office 365 requirements

Before choosing this migration strategy, ensure your on-premises solution meets the prerequisites of a successful deployment of both environments. For instance, Office 365 Business plans do not support hybrid setups. (Check out our Office 365 License Comparison here.)

Check the version of your Exchange

Only select Exchange versions that support hybrid Exchange deployments. For instance, an Exchange 2016/Office 365 hybrid deployment only works with Exchange 2016, 2013 and 2010. If you’re using Exchange 2007 or 2010, you’ll have to upgrade to a newer version before migrating. If you have the latest version of Exchange, you should have at least one server operating under the Mailbox role.

Update mailbox users to Office 365

When you move mailboxes between environments, all mailbox users should be updated to Office 365, including Exchange ActiveSync devices.

Many of these clients are automatically reconfigured when the mailbox is moved to Office 365. Older devices may have issues, so be sure to check which devices support Exchange ActiveSync.

Devise a plan to configure permissions within Office 365

Permissions such as Send As and Receive As, which are applied to the mailbox, migrate to Office 365 explicitly. Non-explicit, or inherited, permissions on mailbox and non-mailbox objects don’t migrate over.

Because of this, you should have a plan to configure permissions within Office 365. You can use Add-RecipientPermission and Add-MailboxPermission Windows PowerShell to help set the proper permissions in Office 365.

Which components and services are available in a hybrid deployment?

You can expect to see several services and components in a hybrid environment. Some include:

Exchange Online

Office 365 includes Exchange Online, which you’ll use in a hybrid deployment.

You’ll need to purchase a license for every mailbox you migrate or create in the hybrid environment using Exchange Online. This is why many businesses use this solution as a transitional step before a complete Office 365 migration.

Azure AD authentication and synchronization

AD authentication is free and serves as a trust broker between the on-premises Exchange and Exchange Online, though you’ll need a federation trust with the AD authentication. AD sync uses Azure AD Connect to duplicate an on-premises AD for the mail-enabled objects available in Office 365 to support the global access list.

Azure AD Connect

In the hybrid environment, you will need to deploy Azure AD Connect on your on-premises server to sync Office 365 with your on-premises AD.

Migrate with confidence

Ready to complete your hybrid Exchange deployment? Or still unsure whether it’s the right solution for your business? Agile IT’s cloud specialists can help.

Contact us here to discuss your project needs.