Exchange Online for US government environments

This article provides an overview of feature differences between the US government cloud and the commercial cloud as listed in the Exchange Online service description. Exchange Online is available for the Government Community Cloud (GCC), GCC High, and Department of Defense (DoD) environments.

For more information about the government cloud, including eligibility and purchasing, see Microsoft 365 Government - how to buy. To compare Office 365 Government plans, see Office 365 Government plans.

To learn about required endpoints when managing network connectivity, see the Office 365 U.S. Government GCC High endpoints or Office 365 U.S. Government DoD endpoints.

In addition to enjoying the features and capabilities of Office 365, organizations benefit from the following features unique to the US government cloud environments:

• Your organization’s customer content is logically segregated from customer content in the commercial Office 365 services.

• Your organization’s customer content is stored at rest within the United States.

• Access to your organization’s customer content is restricted to screened Microsoft personnel.

• The government cloud environments comply with certifications and accreditations often required for US Public Sector customers.

It is our general intent to deliver all Exchange commercial features and functionality to the government cloud environment. That said, some features aren't available because of the requirements of government cloud customers. Other features are coming to the government environments but aren't yet available. Refer to the following sections to learn about feature availability in the government cloud environments.

Exchange Online features

The following table outlines whether specified Exchange Online features are available within the GCC, GCC High, and DoD environments. When there are nuances regarding the statement of support (or lack thereof), additional context is provided.

¹ Outlook on the Web can be used in scenarios when Outlook for Windows is unable to display the IRM protected messages due to cross-boundaries restrictions (GCC High / Non-GCC High scenarios).
² Only egress to specific address spaces the customer can prove they own are allowed, so this precludes third-party services and broad IP ranges used by mobile devices.

Feature nuances within GCC High and DoD environments

Connectivity with third-party services  

Both GCC High and DoD environments are restricted environments that require explicit approval and configuration of outbound connections. Additionally, Microsoft can't accommodate requests to allow outbound access from these environments to commercial cloud services (Commercial Office 365, Google GSuite, Amazon Web Services, and so on).

Due to these restrictions, features that rely on this outbound connectivity from the GCC High/DoD environments are generally not supported, including:

• Connected accounts - Users can't add/sync accounts (Google, POP/IMAP, and so on).

• Support for third-party file storage providers - Only the user’s OneDrive for Business account within GCC High/DoD can be accessed from within the various Outlook clients for the purpose of attaching/sharing files. Third-party storage accounts (Dropbox, Box, Google Drive) can't be added.

• Connectivity with social networks, such as Facebook or LinkedIn.

Microsoft Entra ID B2B collaboration

Microsoft Entra ID B2B collaboration is currently supported only between organizations that are both within Azure US Government cloud and that both support B2B collaboration

Additionally, B2B users as guests in Office 365 groups aren't supported in GCC High and DoD environments. 

For more information and the latest updates, see Azure Government Security + Identity.

Message Encryption behavior across GCC High/DoD boundary

If you plan to use Message Encryption in a GCC High environment, be aware of these unique characteristics about the recipient experience:  

• When sending encrypted email from GCC High or DoD to recipients in the same environment:

  • Senders can manually encrypt emails in Outlook for PC and Mac and Outlook on the web, or organizations can set up a policy to encrypt emails using Exchange mail flow rules.
  • Recipients inside GCC High/DoD receive the same inline reading experience in Outlook for PC and Mac and Outlook on the web as all other Office 365 users.

• When sending encrypted email from GCC High to recipients outside of that environment (including DoD, GCC and Commercial):

  • Senders inside GCC High can send encrypted email outside of the GCC High boundary.
  • All recipients outside GCC High, including DoD, commercial Office 365 users, Outlook.com users, and other users of other email providers, receive a notification mail. This notification mail redirects the recipient to the encrypted message portal where the recipient can read and reply to messages.
  • Sharing of documents and downloaded email attachments with users in the commercial cloud is currently not available. Encrypted attachments can only be previewed in the encrypted message portal.

Free/Busy federation

Federated sharing, including free/busy information, is currently subject to several important limitations in the DoD environments.

In the GCC High environment:

• Federation trust (including bidirectional free/busy sharing) is supported between tenants within GCC High, to tenants in GCC and commercial clouds, and through hybrid coexistence (Exchange 2013 or later).

In the DoD environment:

• Federation trust (including free/busy sharing) is currently supported only between tenants within the DoD environment. It isn't supported between DoD tenants and GCC, GCC High, or commercial tenants.

Client configuration

Additional steps are involved in deploying and configuring Office ProPlus (including Outlook). For a detailed description of these steps, see Guidance for deploying Microsoft 365 Apps for enterprise in a GCC High or DoD environment.

Outlook for iOS and Android is also available for GCC High and DoD environments. To learn more about feature limitations and management in those environments, see Using Outlook for iOS and Android in the Government Community Cloud.

Add-ins in Outlook and Outlook Web App  

Only some OWA and Outlook add-ins are available in GCC High and DoD. My Templates and Suggested Meetings are available and expected to function. Only the five default OWA add-ins are supported. Integration with third-party applications is possible, however, those integrations aren't covered by Microsoft compliance promises for GCC High or DoD. Customers should familiarize themselves with third-party data handling practices and compliance promises before configuring the add-on for their organization.

Feature nuances within GCC environments for Microsoft To Do

*Any other features not mentioned are available in both environments.