We were told by GHL support that the auto BCC sync feature only works in Gmail. If we add the provided BCC email address in the CC or BCC when sending an email to a non-contact in Gmail, the person is created as contact in the CRM.
However, this feature doesn't work in Outlook. You need to send the first email via the CRM to established the two-way sync and there's no way to create contact from Outlook.
Most of our clients are using Outlook and they want to be able to use this feature.