What do different drop slots do in the USPS office?

Lockable Drop Slot Mailbox with Parcel Compartment, Black mailbox drop slot A: A door mail slot is a small, rectangular opening in the front door through which a mail carrier can deliver mail Its benefits include usability and security mailbox slot for door In my neighborhood we have mailbox lockers They have thin slots for dropping off letters to be picked up I do have a small side gig

mailbox slot in wall Mail slots, when the majority of mail was letters, were accepted as a delivery method The negative aspect of a mail slot is folding and bending