code: def header(self, name, value):
          
          self.message += "{}: {}\r\n".format(name, value)
          logger.debug('<{}> Received {} header'.format(self.id, name))
          if name.lower().startswith(self.header_prefix.lower()):
              self.remove_headers.append(name)
              logger.debug('<{}> Going to remove {} header'.format(
                  self.id, name))
          return Milter.CONTINUE
docs: Store all message headers, optionally clean them up.
  
          This simply stores all message headers so we can send them to DSPAM.
          Additionally, headers that have the same prefix as the ones we're
          about to add are deleted.