//---------------------------------------------------------------------------
      // HELO command request handling.
      //---------------------------------------------------------------------------      

      if(command(input) == "HELO") {

         if(input.length() > 5) {
            string hostName = input.substr(5);
         }

         else {

            // TODO: Provide error message demanding identity here. 
            // 
         }

         cout << "250 " << getHostName() << CRLF;
         state = "READY";
      }