law: Information Technology Act, 2000
  12. Acknowledge of receipt.- 
  (1) Where the originator has not agreed with
  
  the addressee that the acknowledgement of receipt of electronic record be given
  
  in a particular form or by a particular method, an acknowledgement may be given
  
  by- 
  (a) any communication
  
  by the addressee, automated or otherwise; or
  (b) any conduct of the
  
  addressee, sufficient to indicate to the originator that the electronic record
  
  has been received.
  Where the originator has stipulated that the
  
  electronic record shall be binding only on receipt of an acknowledgement of
  
  such electronic record by him, then, unless acknowledgement has been so
  
  received, the electronic record shall be deemed to have been never sent by the
  
  originator.
  Where the originator has not stipulated that
  
  the electronic record shall be binding only on receipt of such acknowledgment,
  
  and the acknowledgement has not been received by the originator within the time
  
  specified or agreed or, if no time has been specified or agreed to within a
  
  reasonable time, then, the originator may give notice to the addressee stating
  
  that no acknowledgement has been received by him and specifying a reasonable
  
  time by which he acknowledgement must be received by him and if no
  
  acknowledgement is received within the aforesaid time limit he may after giving
  
  notice to the addressee, treat the electronic record as tough it has never been
  
  sent.