When people rent a property they have a right to receive their mail. I don't think the law will allow the owner to control mail to the guest who rented the property.
The front desk cannot control access to the property once the keys are checked out. I cannot access the property either to check on number of guests without violating their privacy.
The problem is wth AirBnB: hey are not willing to help and pay with the Host Guarantee and I don't have any access to security deposit held with AirBnB.
I am getting more in favor of VRBO or HomeAway where you can withhold deposit if there are damages or extra guests...