Since most mailboxes are between 10 to 12 inches tall at their tallest point, the total height will be anywhere between 51 to 57 inches at the top of the mailbox. The opening of the mailbox needs to be set between six and eight inches back from the curb, and the mailbox post should be buried 24 inches into the ground. The average mailbox meets the USPS requirements of standing on a post between 41 and 45 inches high. We’ll explore options for other types of mailboxes below. What is the Ideal Mailbox Shape and Height?īelow, we’ll look at the height requirements for mailboxes placed near the curb which have mail delivered by a postal worker in a postal vehicle.So My Mailbox Plans Have to Go To Washington DC?.Mailboxes Have to Meet the Requirements Set by the USPS:.