Abstract: A single-door security rural mailbox having a front closure that can be accessed by the rural mail carrier and the owner of the mailbox from the same opening. The mailbox has a key operated locking mechanism for locking the closure. The owner of the mailbox locks and sets the closure in a set position allowing the mail carrier to open the closure once. The mail carrier then closes the closure with sufficient force so that the locking mechanism passes the set position and engages in a locked position. Thereafter, the closure can only be unlocked by the owner with a key who then sets the lock and closure for the next mail delivery where again the mail carrier can open and then shut the closure.