Whoever knowingly and willfully obstructs or retards the passage of the mail, or any carrier or conveyance carrying the mail, shall be fined under this title or imprisoned not more than six months, or both.
18 U.S. Code § 1701 - Obstruction of mails generally
Words “carriage, horse, driver or”, “car, steamboat”, and “or vessel” were omitted as covered by “any carrier or conveyance”.
The punishment provision is derived from said section 324 rather than from section 325 which provided only a fine of not more than $100 and related only to ferrymen.
1994—Pub. L. 103–322 substituted “fined under this title” for “fined not more than $100”.