When you attempt to Test and Enable a mailbox in Dynamics 365, one of the following alerts are logged:
"Email can't be received for the mailbox <Mailbox Name> because the associated user doesn't have a valid Microsoft Dynamics 365 license. The mailbox didn't synchronize. A notification about this is posted on the alerts wall for the owner of the email server profile Microsoft Exchange Online.
Email Server Error Code: IncomingEmailNoLicenseAssigned"
"Email can't be sent for the mailbox "Test Message" because the associated user doesn't have a valid Microsoft Dynamics 365 license. The mailbox didn't synchronize. A notification about this is posted on the alerts wall for the owner of the email server profile.
Email Server Error Code: OutgoingEmailNoLicenseAssigned"
The user does not have a Microsoft Dynamics 365 license assigned or the owning user has their Access Mode set to Administrative.
Verify the user has a Dynamics 365 license
1. Assign a Microsoft Dynamics 365 license to the user. Refer to the Add a license to a user accountsection of the Create users and assign Microsoft Dynamics 365 (online) security roles article.
NOTE: After assigning the Microsoft Dynamics 365 license to the user, it may take a few minutes for this change to sync from Office 365 to Dynamics 365.
Verify the user is not in Administrative access mode
1. Sign into your Dynamics 365 organization as a user with the System Administrator role.
2. Navigate to Settings and then click Email Configuration.
3. Click Mailboxes.
4. Change the selected view from My Active Mailboxes to Active Mailboxes.
5. Open the user's mailbox record.
6. Click the user selected in the Owner field to open the User record.
7. Expand the Administration tab.
8. Verify the Access Mode is set to Read-Write.
Test and Enable the Mailbox Again
1. Open the mailbox record if it is not already open.
2. Click the Test & Enable Mailbox button.
3. Wait for the Test & Enable process to complete. If the test results are not Success, review the Alerts area within the mailbox record.