law: Indian Post Office Act, 1898 
  53. Penalty for opening, detaining or delaying postal
  
  articles
  Whoever, being an officer
  
  of the Post Office, contrary to his duty, opens, or causes or suffers to be
  
  opened, any postal article in course of transmission by post, or willfully
  
  detains or delays, or causes or suffers to be detained or delayed, any such
  
  postal article, shall be punishable with imprisonment for a term which may
  
  extend to two years, or with fine or with both:
  Provided that nothing
  
  in this section shall extend to the opening, detaining or delaying of any
  
  postal article under the authority of this Act or in obedience to the order in
  
  writing of the Central Government or the direction of a competent Court.