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Scoping Microsoft Graph application permissions to specific Exchange Online mailboxes

Today we’re excited to announce the release of the Application Access Policy feature for Exchange Online PowerShell. This feature allows Exchange Online administrators to scope application permissions for Microsoft Graph to allow access to specified mailboxes in their Office 365 tenant.

Why would you need to do this? Well, imagine Contoso, an Office 365 customer that has thousands of employees spread across multiple departments. Contoso has built and deployed an appointment booking app that helps their customers book service appointments with specialist technicians employed by the company.

The app Contoso built uses Microsoft Graph to identify free appointment times on the technicians’ calendars and uses them to book appointments. Because the app requires access to multiple technicians’ mailboxes, it uses the OAuth 2.0 client credentials grant flow, and application permissions were granted to it, enabling the app to access all mailboxes in the organization, not just the mailboxes belonging to technicians.

Using Application Access Policies, Contoso administrators can now restrict the app’s access to only the technicians’ mailboxes via a security group, and disallow its access to other mailboxes. You can use the following links to learn more about this feature.

Additional resources

  1. Scoping application permissions to specific Exchange Online mailboxes
  2. New-ApplicationAccessPolicy
  3. Get-ApplicationAccessPolicy
  4. Remove-ApplicationAccessPolicy
  5. Set-ApplicationAccessPolicy
  6. Test-ApplicationAccessPolicy

Please let us know if you have additional feedback about Microsoft Graph or suggestions for new functionality.

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