Mailbox Supports

The Postal Service does not regulate mailbox supports in any way except for purposes of carrier safety and deliv­ery efficiency. Posts and other supports for curbside mail­boxes are owned and controlled by customers, who are responsible for ensuring that posts are neat and adequate in strength and size. Heavy metal posts, concrete posts, and miscellaneous items of farm equipment, such as milk cans filled with concrete, are examples of potentially dan­gerous supports. The ideal support is an assembly that bends or falls away when struck by a vehicle. Post or sup­port designs may not represent effigies or caricatures that disparage or ridicule any person. Customers may attach the box to a fixed or movable arm. POM 632.5 specifies postal regulations regarding construction and placement of mailboxes and supports on motorized city, rural, and con­tract delivery service routes.

The Federal Highway Administration (FHWA) has deter­mined that wooden mailbox supports no larger than 4 inches by 4 inches, or a 2-inch diameter standard steel or aluminum pipe, buried no more than 24 inches, should safely break away if struck by a vehicle. According to FHWA, the mailbox must also be securely attached to its post to prevent separation if struck. See Exhibits E (page 22) and F (page 23) for examples of mailbox mountings and supports suggested by the FHWA.