We recommend that you contact your local utility companies or your state's "Call Before You Dig" service prior to the installation of your Mailbox of Distinction. In some states this is required by law. You should know where buried utilities (electric, gas, telephone, cable, water) are located before you dig.
The following is an excerpt from the U.S. Postal Service Standard, Mailboxes, Curbside USPS – STD – 7B:
“Customers are required to contact the local post office before installing the mail box to ensure its correct placement and height at the street. Generally mail boxes are installed at a height of 41-45 in. from the road surface to inside floor of the mail box or point of mail entry (locked designs) and are set back 6-8 in. from front face of curb or road edge to the mailbox door.”
See also: USPS Compliance Statement