Pro-DF Vertical Mailbox with Lock - 4-in x 8-in x 14-in - Black

Versatile Front Loading Single Column Commercial Mailbox with 4 4 slot mailbox I think the introductions to each mechanism on MSDN answers this: Mailslots: A mailslot is a mechanism for one-way interprocess 4 slot Metal 4 Slot Industrial Mailbox Wall Storage

4d toto slot Vertical mailbox with 4 doors, front load, surface mounted; Ideal replacement Door Identification: Number and name slot with paper cards for field