law: General Clauses Act, 1897
  27. Meaning of service by post
  Where any 13[Central Act] or Regulation made after the
  
  commencement of this Act authorizes or requires any document to be served by
  
  post, where the expression "serve" or either of the expressions
  
  "give" or "send" or any other expression is used, then,
  
  unless a different intention appears, the service shall be deemed to be
  
  effected by properly addressing, pre-paying and posting by registered post, a
  
  letter containing the document, and, unless the contrary is proved, to have
  
  been effected at the time at which the letter would be delivered in the
  
  ordinary course of post.