Appointments, contacts, and tasks can't be synchronized because the email address of the mailbox {0} is configured with another ...

Appointments, contacts, and tasks can't be synchronized because the email address of the mailbox {0} is configured with another Microsoft Dynamics 365 organization. The best practice is to overwrite the configuration when you test and enable the mailbox in your primary organization. Also, change the synchronization method for your mailbox in non-primary organizations to None.