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Plan an Exchange Online hybrid deployment in Office 365


Topic Last Modified: 2014-10-21

Summary: Describes the requirements and considerations for a hybrid Exchange deployment.

To provide the smoothest migration to the Office 365 environment, or to keep a mix of on-premises mail users and Office 365 mail users for a long time, organizations can configure an Exchange hybrid deployment.

A hybrid deployment provides a unified email experience for your Office 365 deployment. It enables users who have mailboxes in your on-premises Exchange Server environment and users who have Exchange Online mailboxes to find one another in the global address list (GAL), and to send, receive, and reply to email regardless of which system is hosting their mailbox.

A hybrid deployment can be either Exchange 2013-based or Exchange 2010-based. Both Exchange 2013 CU2 and Exchange 2010 SP3 include support for hybrid deployments using the Hybrid Configuration wizard, components designed to help you easily configure hybrid deployments. Used stand-alone, or together with the Exchange Deployment Assistant, this wizard provides Exchange administrators with a streamlined process to create and configure a hybrid deployment between on-premises Exchange and Office 365 organizations.

A hybrid deployment provides these advantages:

  • Exchange Online users and on-premises users can share free/busy calendar data.

  • Administrators can use the Exchange Admin Center (EAC) with Exchange 2013 or the Exchange Management Console (EMC) with Exchange 2010 to manage both the Exchange Online and on-premises Exchange mail environments.

  • Administrators can use powerful and familiar Exchange management tools to move users to Exchange Online.

  • Outlook profiles for users are automatically updated to the Exchange Online environment when the Exchange hybrid deployment and Autodiscover are configured appropriately. Administrators do not have to manually reconfigure Outlook profiles or resynchronize .OST files after they move users’ mailboxes.

  • Outlook Web App redirection allows for redirection from the on-premises Outlook Web App environment to the Office 365 Outlook Web App environment. You specify a target URL for your organization (for example, www.outlook.com/contoso.com).

  • MailTips, out-of-office messages, and similar features understand that Office 365 and on-premises users are part of the same organization.

  • Delivery reports and multi-mailbox search work with users who are on-premises and those working in Exchange Online.

  • Authentication headers are preserved during cross-premises mail flow. So, all mail looks and feels like it is internal to the company (for example, recipient names resolve in the GAL).

  • If necessary, administrators can easily move mailboxes back to the on-premises Exchange environment.

For more information about Exchange 2013-based hybrid deployments, see Exchange Server 2013 Hybrid Deployments.

For more information about Exchange 2010-based hybrid deployments, see Understanding Hybrid Deployments with Exchange 2010 SP3.

You should consider the following before you implement an Exchange hybrid deployment:

  • Mailbox permissions  On-premises mailbox permissions such as Send As, Receive As, and Full Access that are explicitly applied on the mailbox are migrated to Exchange Online if the tenant in Exchange Online has been fully synchronized using Dirsync or AAD Sync. Inherited (non-explicit) mailbox permissions such as permissions applied to the mailbox database and any permissions on non-mailbox objects (such as distribution lists or a mail-enabled user) are not migrated. Therefore, you should recreate these permissions in Exchange Online using the Add-MailboxPermission or Add-RecipientPermission cmdlets.

  • Cross-premises permissions Mailbox permissions such as Send As, Receive As, and Full Access are not supported if the user trying to access the mailbox is in Exchange Online but the target mailbox is on-premises, or vice versa. Typically, when migrating a user mailbox from on-premises to Exchange Online, in order to overcome this limitation, mailboxes belonging to users who have access to the first mailbox should also be migrated at the same time to ensure the delegate scenarios continue to work.

  • Offboarding  As part of ongoing recipient management, you might have to move Exchange Online mailboxes back to your on-premises environment.

    For more information about how to move mailboxes in an Exchange 2010-based hybrid deployment, see Move an Exchange Online mailbox to the on-premises organization.

    For more information about how to move mailboxes in an Exchange 2013-based hybrid deployment, see Move Mailboxes Between On-Premises and Exchange Online Organizations in 2013 Hybrid Deployments.

  • Multi-forest Active Directory environments  If your organization implements multiple on-premises Exchange organizations, you must deploy Exchange 2013 SP1 or greater servers in your on-premises organization to configure a hybrid deployment with Office 365.

    For more information, see Hybrid Deployments with Multiple Active Directory Forests

There are several requirements for configuring an Exchange hybrid deployment with your on-premises Exchange environment:

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