Hybrid deployments between your on-premises and Office 365 organizations can be configured using either Exchange 2013 or Exchange 2010 servers. Depending on which version of Exchange you deploy in your on-premises organization to configure hybrid, your hybrid deployment will be either an Exchange 2010-based hybrid deployment or an Exchange 2013-based hybrid deployment. Following is a brief description of each deployment type:

• Exchange 2010-based hybrid deployment   Exchange 2010-based hybrid deployments use Exchange 2010 servers to connect to the Microsoft Exchange Online Protection (EOP) service (formerly known as Forefront Online Protection for Exchange) included with all Office 365 tenants. Exchange 2010-based hybrid deployments can either be on-premises organizations that are homogenous Exchange 2010 organizations, or Exchange 2003 and Exchange 2007 on-premises organizations that have added Exchange 2010 servers as part of configuring a hybrid deployment with Office 365. This includes adding servers with either the Exchange 2010 Client Access or Edge Transport server roles.
  
   
  
  Exchange 2010-based hybrid deployments are compatible with the newest version of Office 365, provided some requirements are met. Compatibility with Office 365 allows organizations to remain configured as Exchange 2010-based hybrid deployments if they choose not to use the new features of Exchange 2013.
  
   
  
  
• Exchange 2013-based hybrid deployment   Exchange 2013-based hybrid deployments use Exchange 2013 servers to connect to the EOP service included with all Office 365 tenants. Exchange 2013-based hybrid deployments can either be on-premises organizations that are homogenous Exchange 2013 organizations, or Exchange 2007 and Exchange 2010 on-premises organizations that have added Exchange 2013 servers as part of configuring a hybrid deployment with Office 365. All on-premises Exchange 2013 servers must have installed Cumulative Update 1 (CU1) or greater for Exchange 2013 to support hybrid functionality with Office 365. For more information, see Cumulative Updates for Exchange 2013.
  
   
  
  Exchange 2013-based hybrid deployment also includes scenarios where on-premises organizations add servers with the Exchange 2010 SP3 Edge Transport server role to Exchange 2013 organizations to use the benefits of a perimeter network. For more information about Exchange 2013-based hybrid deployments, see Exchange Server 2013 Hybrid Deployments.
  
  

Important:
Exchange 2003 on-premises organizations can’t configure a hybrid deployment using Exchange 2013 servers. These organizations must use Exchange 2010-based hybrid deployments to configure coexistence with Office 365.

Microsoft initiates Office 365 tenant upgrades. When their Office 365 tenant is eligible for upgrade to the newest version of the service, Office 365 administrators receive an email notification from Microsoft. While the Office 365 tenant upgrade process is fully automated and doesn’t require any additional deployment requirements for cloud-only organizations, organizations with Exchange 2010-based hybrid deployments do require a few basic checks and actions as part of the Office 365 upgrade process.

For more information, see Office 365 Service Upgrade Center for Enterprise.

As part of the Office 365 tenant upgrade process, administrators need to conduct two administrative steps in order for Exchange 2010-based organizations to be fully functional when the Office 365 tenant is upgraded to version v15:

• Exchange 2010 Service Pack 3   Exchange Server 2010 SP3 is required for all Exchange 2010 Client Access and Hub Transport servers in an Exchange 2010-based hybrid deployment that are Internet-facing and connect to Office 365 tenant version v15 or higher. This requirement also includes any Exchange 2010 Edge Transport servers that are configured to connect with Office 365 as part of a hybrid deployment.
  
   
  
  We recommend installing Exchange 2010 SP3 on your Exchange 2010 servers and management workstations in your on-premises organization before you accept the Office 365 update invitation. Exchange 2010 SP3 contains updates to the Exchange Management Console (EMC) that allow it to connect to the remote Exchange Online organization, as well as updating the management experience for the remote Exchange Online organization.
  
   
  
  

  Important:

  If you don’t install Exchange 2010 SP3 prior to your Office 365 tenant upgrading to version v15, don’t worry. Your hybrid deployment-related features and secure mail between your on-premises and Exchange Online organizations will continue to function normally. You’ll receive a prompt to upgrade to Exchange 2010 SP3 when you try to access the remote Exchange Online organization node in the EMC. If you need to manage the organization configuration setting for the Exchange Online organization prior to updating to Exchange 2010 SP3, you can use the Exchange admin center (EAC) in the Office 365 tenant. To learn more about hybrid management and the version v15 Office 365 tenant, see Understanding Hybrid Management in Exchange 2010 Hybrid Deployments. To learn more about other updates included with Exchange 2010 SP3, see What's New in Exchange 2010 SP3.

   
  
  
• Hybrid Configuration wizard   After you’ve installed Exchange 2010 SP3 and completed the update to your Office 365 tenant, you must run the Hybrid Configuration wizard again. You don’t need to make any hybrid configuration changes if there aren’t any changes to be made, but the wizard still needs to run to properly update the HybridConfiguration Active Directory object.
  
  

The Exchange Online service included as part of an Office 365 tenant is based on Exchange Server. When the Office 365 tenant is upgraded and the tenant version changes, the version of Exchange Online also changes. Following is specific information about tenant versions currently available:

• Office 365 tenant version v14   Office 365 tenant version 14 includes the Exchange Online service that is based on Exchange 2010. This tenant version is identified by version number 14.0.000.0 and higher.
  
  
• Office 365 tenant version v15   Office 365 tenant version 15 includes the Exchange Online service that is based on Exchange 2013. This tenant version is identified by version number 15.0.000.0 and higher.
  
  

Note:
If you’re unsure what version of the Office 365 tenant is configured as part of your hybrid deployment, see the Verify Office 365 tenant version and status section later in this topic.

The Office 365 tenant version and each Exchange-based hybrid deployment requirements are listed in the following table.

Note:
1 Blocked in Exchange 2013 setup 2 Tenant upgrade notification provided in Exchange Management Console 3 Requires at least one on-premises Exchange 2010 SP2 server 4 Requires at least one on-premises Exchange 2010 SP3 server 5 Requires at least one on-premises Exchange 2013 (CU1) or greater server

Verify Office 365 Tenant Version and Status