Dynamics 365 Outlook Client Track email issue and button is not working.

Problem:

After Upgrading to dynamics 365. Dynamics 365 outlook client is working properly. outlook client Track Emails and set Regarding button is not working.  when trying to track emails then receiving errors "You cannot tract this item because your mailbox record in dynamics 365 isn't enabled. Contact your dynamics 365 administrator to enable your mailbox." 

Resolution:

To resolve this disabled mailbox tracing problem in dynamics 365 outlook client, you simply need to go to your CRM email configuration and open the mail box configuration of users facing an issue or select the all mailboxes and click the "Test & Enable Mailboxes" button.

After clicking this button, system automatically start enabling mailboxes and send test email to mailbox. you will also see the notification "Email configuration test is in-progress."

and you can also track the progress using the alerts of mailbox.

Note: Please inform your mailbox user before enabling and test specially for external client. because when you perform this activity. system will send test email to that specific mailbox which create confusion for user.