dumb USPS mail question- outgoing mail door slot?

Mail Slots - mail door slot This is a mail slot sleeve is constructed from stainless steel It lines the cutout in your door that receives mail The sleeve is designed for through door mail door slot Add functionality and style to your doors with our mail slots Designed for durability, they provide a secure way to receive mail

mail slot sleeve Description · May be used for · Made of brass · Letter size mail slot overall dimensions are 8-34″W x 2-78″H · Rough opening dimensions are 6-78″W x 1-3