Outdoor mailboxes typically are positioned close to roads. Therefore, such a mailbox is susceptible to being hit by a motor vehicle, or by other objects such as snow plowed by a snowplow, or even by vandals. The mailbox post is then vulnerable to being broken.
It is known to configure a mailbox post so that it has a flexible joint, thereby allowing the mailbox post to bend rather than break. See Dunn (U.S. Pat. No. 6,223,982). Dunn discloses installing a non-circular spring wire between the upper and lower parts of the mailbox post, the spring being positioned vertically, so that the mailbox post will return to a vertical position after being hit.
However, there are several drawbacks to Dunn's configuration. First, Dunn does not disclose that the spring unit is distinct from the post, and thus if any part of Dunn's post becomes damaged then the entire thing (including the joint) either becomes useless or must be repaired. Likewise, the invention of Dunn replaces an existing mailbox post, instead of being adaptable to an existing mailbox post.
Also, Dunn requires a non-circular elastic element in order for the mailbox post to properly align with a horizontal axis, but such a spring is not as strong and durable as a circular spring. This non-circular elastic element also makes assembly and disassembly difficult, while putting great stress on the parts that secure the non-circular spring to the rest of the mailbox post. Moreover, the tension of Dunn's elastic piece is not adjustable.