Abstract: A self-locking receptacle, such as a rural mailbox, includes a housing having an open end and a closure movably mounted on the housing for closing and opening the end. A latching member is fixedly and immovably attached to and is located within the housing adjacent to the open end. A locking assembly is attached to the closure for contacting and selectively interlocking with the latching member when the closure is closed for enabling the closure to be opened and then closed only once without requiring unlocking and disengaging of the locking assembly from interlocking relationship with the latching member.