code: def receive_hardbounce_post(self, post_params):
          
          if isinstance(post_params, dict):
              required_params = ['action', 'email', 'sig']
              if not self.check_for_valid_postback_actions(required_params, post_params):
                  return False
          else:
              return False
  
          if post_params['action'] != 'hardbounce':
              return False
  
          signature = post_params['sig']
          post_params = post_params.copy()
          del post_params['sig']
  
          if signature != get_signature_hash(post_params, self.secret):
              return False
  
          # for sends
          if 'send_id' in post_params:
              send_id = post_params['send_id']
              send_response = self.get_send(send_id)
              if not send_response.is_ok():
                  return False
              send_obj = send_response.get_body()
              if not send_obj or 'email' not in send_obj:
                  return False
  
          # for blasts
          if 'blast_id' in post_params:
              blast_id = post_params['blast_id']
              blast_response = self.get_blast(blast_id)
              if not blast_response.is_ok():
                  return False
              blast_obj = blast_response.get_body()
              if not blast_obj:
                  return False
  
          return True
docs: Hard bounce postbacks