(1) willfully opens or reads, or causes to be read, any sealed letter not addressed to himself, without being authorized to do so, either by the writer of such letter or by the person to whom it is addressed; or
(2) without the like authority, publishes any of the contents of such letter, knowing the same to have been unlawfully opened—
shall be fined not more than $50 or imprisoned not more than 30 days, or both.