Multi-unit mailbox with replaceable letter drop structure

A multi-user mail box including a letter drop assembly which is susceptible to easy replacement by a delivery person without requiring substantial disassembly of the mail box. The letter drop assembly includes a slotted body held in inserted relation between cross-bars extending transverse to vertical frame members of an access door structure. The slotted body includes upper and lower open grooves oriented in opposing relation to the adjacent cross-bars. Retention pin elements are inserted axially into the grooves thereby holding the slotted body in place. The slotted body may be replaced by displacement of the retention pin elements.