dumb USPS mail question- outgoing mail door slot?

Mail Slot Door - door mailbox slot MAIL SLOT BASKET CATCHER INCLUDED: Our D30-S door mailbox slot comes with an extra-large mail catch, keeping your important letters from scattering on the floor door mail slot blocker The letterbox flap is attached to the door and thus enables letters to reach the vestibule directly It is made of 2 mm thick polished stainless steel V2A

door slot lock This pretty and functional Mail Slot is made from solid brass material Mail slot has flaps on both sides of the door The exterior is a spring-loaded flap