law: Indian Post Office Act, 1898 
  66. Penalty for detention of letters on board vessel
  
  arriving in port
  (1) Whoever, being
  
  either the master of a ship arriving at any port in 5[India] or any
  
  one on board, knowingly has in his baggage or in his possession or custody,
  
  after the postal articles on board or any of them have been sent to the post
  
  office at the port of arrival, any postal article within the exclusive
  
  privilege conferred on the Central Government by section 4, shall be punishable
  
  with fine which may extend to fifty rupees for every such postal article as
  
  aforesaid.
  (2) Whoever, being
  
  such master or other person as aforesaid, detains any such postal article as
  
  aforesaid after demand made for it by an officer of the Post Office, shall be punishable
  
  with fine which may extend to one hundred rupees for every such postal article.