After you click the Test & Enable Mailbox button on a mailbox record in Dynamics 365 (online), you encounter the following alert:
"An internal Microsoft Dynamics 365 error occurred while synchronizing appointments, contacts, and tasks for the mailbox <Mailbox Name>. The owner of the associated email server profile <Email Server Profile Name> has been notified. The system will try again later.
Email Server Error Code: Crm.8004d24b.The user has not been assigned any License"
The user does not have a Dynamics 365 license assigned in Office 365.
Assign a Dynamics 365 license to the user.
NOTE: After assigning a Dynamics 365 license to the user in the Microsoft Online Portal, it may take a few minutes for the license information to sync to Dynamics 365.
For step by step instruction for how to assign a Dynamics 365 license to a user, refer to the following article:
Purchase and assign Dynamics 365 (online) licenses