Abstract: A mailbox assembly, includes an upstanding post, installable alongside a roadway, and a mailbox support structure swingably supported on the post, for rotation in a horizontal plane, is described. In the event that a vehicle should leave the roadway and crash into the mailbox, the support structure will swing out of the vehicle path to prevent destruction of the mailbox or support structure. The support structure includes a vertical shaft that is releasably retained in a normal operating position in which the mailbox is accessible to the driver of a vehicle. The support structure can be deflected rotationally by a vehicle crash force, but is resistant to smaller forces, e.g. wind forces or manual forces.