HOW TO INSTALL A MAILBOX POST Be careful and get help if you need it .
How To Install a Mailbox Post
1) Determine the location for your mailbox post in accordance with the specifications outlined by your local post office. Different cities have different regulations, so find out what yours are before you place your post. Federal regulations specify a height of 42 inches from the ground to the base of your mailbox, but you should also check your local ordinances in case height specifications are different where you live.
2) Call your local utility companies to find out if there are any utility lines buried in the area where you plan to dig your mailbox post. Your state may have a "One Call" service that notifies all relevant utility companies that you plan to dig and which will advise you to wait a certain amount of time so that any underground lines may be marked. Look online or in the front of your phone book to find your state's "One Call" number.
3) Dig the hole for your mailbox post 18 to 20 inches deep. Meet the required measurements from the ground to the bottom of the mailbox. Preformed mailbox posts may have an indicator line for the depth of your post. For treated wood posts, account for two inches of rocks at the base of your hole .