class EventMachine::Protocols::SmtpServer

def process_data


it would be a nice idea to add it to the other user-code callbacks.
This was added to deal with a special case in a particular application, but
Unusually, we can deal with a Deferrable returned from the user application.
-- 
def process_data
  unless @state.include?(:rcpt)
    send_data "503 Operation sequence error\r\n"
  else
    succeeded = proc {
      send_data "354 Send it\r\n"
      @state << :data
      @databuffer = []
    }
    failed = proc {
      send_data "550 Operation failed\r\n"
    }
    d = receive_data_command
    if d.respond_to?(:callback)
      d.callback(&succeeded)
      d.errback(&failed)
    else
      (d ? succeeded : failed).call
    end
  end
end