How are you “catching” mail that passes through your door mail slot?

SKYSHALO Through The Wall Mail Slot Off Box - Secure Mail Vault for Mail, Rent, Checks, and Cash

The fully-insulated mailbox system for installation in the door side has flush-mounted, recessed Avantgarde mail slot flaps with finger recess for easy opening

through the wall mail slot Letter Slots · Thru-the-Wall Secure Package Drop Vaults · Door Mail Drop Boxes

through wall mail slot sleeve My best idea to prevent this has been to buy a backless wall-mount mailbox with a locking lid and mount it on the inside of the door over the slot, but I can't