Multi-Geo Capabilities in Exchange Online
In a multi-geo environment, you can select the location of Exchange Online mailbox content (data at rest) on a per-user basis.
You can place mailboxes in satellite geo locations by:
Creating a new Exchange Online mailbox directly in a satellite geo location.
Moving an existing Exchange Online mailbox to a satellite geo location by changing the user's preferred data location.
Onboarding a mailbox from an on-premises Exchange organization directly into a satellite geo location.
This feature does not guarantee email routing through a dedicated geo-specific region (data in transit).
Mailbox placement and moves
After Microsoft completes the prerequisite multi-geo configuration steps, Exchange Online will honor the PreferredDataLocation attribute on user objects in Azure AD.
Exchange Online synchronizes the PreferredDataLocation property from Azure AD into the MailboxRegion property in the Exchange Online directory service. The value of MailboxRegion determines the geo location where user mailboxes and any associated archive mailboxes will be placed. It is not possible to configure a user's primary mailbox and archive mailboxes to reside in different geo locations. Only one geo location may be configured per user object.
When PreferredDataLocation is configured on a user with an existing mailbox, the mailbox will be put into a relocation queue and automatically moved to the specified geo location.
When PreferredDataLocation is configured on a user without an existing mailbox, when you provision the mailbox, it will be provisioned into the specified geo location.
When PreferredDataLocation is not specified on a user, when you provision the mailbox, it will be provisioned in the central geo location.
If the PreferredDataLocation code is incorrect (e.g. a typo of NAN instead of NAM), the mailbox will be provisioned in the central geo location.
Note: Multi-geo capabilities and Skype for Business Online regionally hosted meetings both use the PreferredDataLocation property on user objects to locate services. If you configure PreferredDataLocation values on user objects for regionally hosted meetings, the mailbox for those users will be automatically moved to the specified geo location after multi-geo is enabled on the Microsoft 365 tenant.
Feature limitations for multi-geo in Exchange Online
Security and compliance features (for example, auditing and eDiscovery) that are available in the Exchange admin center (EAC) aren't available in multi-geo organizations. Instead, you need to use the Microsoft 365 Security & Compliance Center to configure security and compliance features.
Outlook for Mac users may experience a temporary loss of access to their Online Archive folder while you move their mailbox to a new geo location. This condition occurs when the user's the primary and archive mailboxes are in different geo locations, because cross-geo mailbox moves may complete at different times.
Users can't share mailbox folders across geo locations in Outlook on the web (formerly known as Outlook Web App or OWA). For example, a user in the European Union can't use Outlook on the web to open a shared folder in a mailbox that's located in the United States. However, Outlook on the Web users can open other mailboxes in different geo locations by using a separate browser window as described in Open another person's mailbox in a separate browser window in Outlook Web App.
Note: Cross-geo mailbox folder sharing is supported in Outlook on Windows.
Public folders are supported in multi-geo organizations. However, the public folders must remain in the central geo location. You can't move public folders to satellite geo locations.
In a multi-geo environment, cross-geo mailbox auditing is not supported. For example, if a user is assigned permissions to access a shared mailbox in a different geo location, mailbox actions performed by that user are not logged in the mailbox audit log of the shared mailbox. Exchange admin audit events are also only available for the default location. For more information, see Manage mailbox auditing.