§ 1229. Sign required on privately-owned vehicle used in delivery of
mail. 1. Every person operating a privately-owned vehicle in delivering
the United States mail to the addressee thereof shall affix to such
vehicle a white sign, visible from the rear, containing the following
statement:

U. S. MAIL
Such statement shall be in black lettering at least four inches in
height.

2. Every person who violates the provisions of this section shall be
punishable by a fine not exceeding twenty-five dollars or by
imprisonment for not more than ten days or by both such fine and
imprisonment.