Optional Outgoing Mail Slot

How do I use an outgoing mailbox? outgoing mail slot Custom Outgoing Mail Slot for Vertical Mailboxes Door Size: 16H x 5-12W Features: Vertical Mailboxes are USPS Approved ONLY for villa slot Some Cluster Box units also contain a slot for Outgoing Mail Mail is collected from this slot by the carrier during regular mail delivery For

spacejammers slot Description: 4-34 W x 12 H outgoing mail slot option on far left door of vertical mailboxes