Request approval by staff member for bookings

Hi, 

is there any way to request an approval from the staff BEFORE sending the confirmation email to the customer? we're facing to have a public booking page but would like also to avoid fake bookings or duplicated.

I've tried setting by powershell "ModerationEnabled" on True to the Scheduling mailbox used for Bookings, but with no difference on before setting the option.

thanks,

Silvio