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When attempting to open the Dynamics 365 App for Outlook, you see the following error:
"We can't open the app because the user's mailbox is inactive."
This error willl appear if your mailbox record in Dynamics 365 is deactivated.
1. Access your Dynamics 365 organization as a user with the System Administrator role.
2. Navigate to Settings, Email Configuration, and then click Mailboxes.
3. Locate the mailbox for the user encountering this error. You may need to switch the view to Inactive Mailboxes.
4. Open the mailbox record and view the Status value at the very bottom of the form. If it appears as Inactive, click the Activate button.
5. After the mailbox is activated, click the Test & Enable Mailbox button and wait for the tests to complete.
NOTE: You may need to refresh the form to see the results. If any of the tests are not successful, view the Alerts section within the mailbox record.
Keywords: dynamics 365, mailbox is inactive, app for outlook