# File lib/em/protocols/smtpserver.rb, line 340
      def process_auth str
        if @state.include?(:auth)
          send_data "503 auth already issued\r\n"
        elsif str =~ /\APLAIN\s?/i
          if $'.length == 0
            # we got a partial response, so let the client know to send the rest
            @state << :auth_incomplete
            send_data("334 \r\n")
          else
            # we got the initial response, so go ahead & process it
            process_auth_line($')
          end
          #elsif str =~ /\ALOGIN\s+/i
        else
          send_data "504 auth mechanism not available\r\n"
        end
      end