def receiver_from_received_header
      if received = message.received
        received = received.first if received.respond_to?(:first)
        received.info[/ for .*?([^\s<>]+)@[^\s<>]+/, 1]
      end
    end
def receiver_from_received_header
      if received = message.received
        received = received.first if received.respond_to?(:first)
        received.info[/ for .*?([^\s<>]+)@[^\s<>]+/, 1]
      end
    end
Heuristic method to find actual receiver of the message.
 May return nil if could not determine.