The United States Post Office has standard guidelines regarding mailboxes. When purchasing a mailbox, the buyer should make sure it has a seal of approval from the Postmaster General. The seal indicates the mailbox design is an approved one.
Do-it-yourself mailbox designs should be submitted to the local postmaster before construction. These, too, must meet standard specifications for size and strength in order to receive formal approval. Also, before a new mailbox is placed on a property, the postmaster needs to be informed about its prospective location. Roadside mailboxes are required to be at least 6 to 8 feet away from the curb. The base of the mailbox must be placed 41 to 45 inches above the ground.