# File lib/em/protocols/smtpserver.rb, line 414
      def process_starttls
        if @@parms[:starttls]
          if @state.include?(:starttls)
            send_data "503 TLS Already negotiated\r\n"
          elsif ! @state.include?(:ehlo)
            send_data "503 EHLO required before STARTTLS\r\n"
          else
            send_data "220 Start TLS negotiation\r\n"
            start_tls
            @state << :starttls
          end
        else
          process_unknown
        end
      end