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Why keep that server after an Exchange Online migration?

Why should a business keep its Exchange Server infrastructure operational after a move to Office 365? Will a hybrid arrangement benefit admins and the organization?

Think it's time to pull the plug on that faithful Exchange Server setup after an Exchange Online migration? Not...

so fast.

Exchange Server mailboxes that stay in the data center give administrators some flexibility -- there's no need to push everything into the cloud and toss the key -- and some Exchange-related functions can perform better on premises.

Here are four reasons to explore an Office 365 hybrid deployment instead of a complete Exchange Online migration.

Hybrid setup provides a mailbox choice

Some businesses prefer the option to keep a few mailboxes on the on-premises Exchange Server and maintain that system rather than rebuild the connection from scratch. A hybrid deployment lets a business natively offboard mailboxes from the Microsoft cloud back to the on-premises Exchange Server. Admins use the remote move migration wizard on the Office 365 tab in the Exchange admin center to send mailboxes to the data center. Without a hybrid setup, the administrator must create new mailboxes and import user information.

Address the large public folder problem

An IT team can sink a lot of time and effort into a comprehensive plan to move large Exchange public folders into Office 365. However, once mailboxes move to the cloud, they can still retain a connection to the on-premises public folders. This means a company can execute its Exchange Online migration but delay the public folder redeployment until a later date -- or keep the public folder in the data center if the migration project isn't feasible.

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Don't forget about application relay

Many businesses routinely use application servers in the data center to relay email messages through Exchange Server. Exchange Online supports message relays from on-premises application servers, but there are throughput limits on the cloud platform. If the message throughput exceeds Exchange Online's cap, the application servers will need Exchange on-premises infrastructure to handle the load.

Hybrid arrangement can ease management

Some organizations use directory synchronization between Active Directory on premises and Azure AD. In this scenario, the source of authority for directory objects in Azure AD remains with the server that runs AD in the data center. Microsoft recommends admins maintain at least one on-premises Exchange Server after the migration for ongoing management of mail-enabled objects in Exchange Online, such as user mailboxes.

Next Steps

Consider key features in Office 365 migration tools

Weigh these factors before moving off Exchange

Stay with Exchange or explore options?

Dig Deeper on Exchange Online administration and implementation