A scheduling conflict was found when saving appointment [appointment subject] from Exchange to Microsoft Dynamics 365 because [user] is unavailable at this time

When viewing the Alerts for a Mailbox record in Dynamics 365, you see the following error alert:

This error is logged if you track an Outlook appointment in Dynamics 365 but Server-Side Synchronization detects a scheduling conflict with another appointment you have at the same time.

1. Within the Dynamics 365 web application, navigate to Settings and click Email Configuration.
2. Click Mailboxes.
3. Open your mailbox record. 
4. Click the Alerts section on the left side of the form.
5. Locate the alert mentioned in the Symptom section of this article.
6. Move your mouse over the alert and you should see options for Yes or No.
7. If you want the appointment to be created in Dynamics 365, click Yes.
8. The next time Server-Side Synchronization processes your mailbox, the appointment should be created in Dynamics 365. This may take up to 15 minutes.