Abstract: Apparatus for protecting cantilevered mailboxes from damage caused by collision with passing vehicles, maintenance equipment and other objects thrown by the plows against the boxes while clearing the roadways. More specifically, the apparatus includes a vertically disposed column anchored in the ground and a laterally projecting arm hingedly secured to the upper portion of the column for swingably supporting the mailbox. A shear pin normally locks the hinge and associated arm and box against rotation. The pin is designed to shear in response to a predetermined torsional stress upon the hinge which stress is produced by the impact of a vehicle or other object striking the box or arm thereby permitting the box and arm to swing to non-obstructing position as the object passes.