Multiple booking notification mode (admin/customer)
In the case you have activated Multiple bookings in one session (Settings > Mode). As a matter of fact, it may be more convenient to group all and send just one notification in this case.
Admin
Choose whether you want to send to your admin a notification per booking or only one for all the bookings.
Customer
Choose whether you prefer to send the customer a notification for each time slot or only one for all the selected timeslots.