(1) Nothing in section 79 shall be deemed to affect the operation of sections 123 and 124 of the Indian Evidence Act, 1872 (1 of 1872), or to apply to any letter, post card, telegram or other document in the custody of the postal or telegraph authorities.
     (2) If any document in such custody is, in the opinion of any Chief Judicial Magistrate, Chief Metropolitan Magistrate, Court of Session or High Court, wanted for the purpose of any Coast Guard Court, such Magistrate or Court may require the postal or telegraph authorities, as the case may be, to deliver such document to such person as such Magistrate or Court may direct.
     (3) If any such document is, in the opinion of any other Magistrate or of any Commissioner of Police or District Superintendent of Police wanted for any such purpose, he may require the postal or telegraph authorities, as the case may be, to cause such search to be made for, and to detain such document pending the orders of any such Chief Judicial Magistrate, Chief Metropolitan Magistrate, Court of Session or High Court.