The opt-in feature helps ensure that appointments are never finalized without your approval. Turning this setting on means that you get to approve prospective meetings before they're added to your calendar. After you've enabled this option, you’ll receive an email at your registered email address whenever a meeting is requested.
You'll also be able to see your unconfirmed meetings within the bookings tab of your Cal.com account. Meetings can be confirmed by either clicking the link you receive in your email or utilizing the unconfirmed meetings tab on your account bookings page.
If you'd like to learn more about our opt-in feature, click here