import java.net.*;
import java.io.*;
import java.lang.*;
import java.util.*;

class SMTPclient
{
   static final int SMTPport = 25;	

   static Socket smtpconn;
   static DataInputStream instream;
   static DataOutputStream outstream;

   // Program: drótposta címek ellenőrzése SMTP kiszolgáló segítségével
   // Használata:
   //    java SMTPclient <host> <user>


   public static void main (String args[])
   {
      String res = new String();

      if (args.length != 2)
      {
         System.out.println("Usage:");
         System.out.println("   java SMTPclient <host> <user>");
         System.exit(1);
      }

      try
      {
         openSMTPconnection(args[0]);
         res = sendMessage("HELO " +
                   java.net.InetAddress.getLocalHost().getHostName());
         res = sendMessage("VRFY " + args[1]);
         System.out.println(res);

         res = sendMessage("QUIT");
         closeSMTPconnection();
      }
      catch(Exception e)
      {
         System.out.println("Error: " + e.toString());
      }
   };

   static void openSMTPconnection (String host) throws IOException
   {
      smtpconn  = new Socket(host, SMTPport);
      instream  = new DataInputStream(smtpconn.getInputStream());
      outstream = new DataOutputStream(smtpconn.getOutputStream());

      String dummy = instream.readLine();
   };

   static void closeSMTPconnection () throws IOException
   {
      smtpconn.close();
   };

   static String sendMessage(String msg) throws IOException
   {
      outstream.writeBytes(msg);

      outstream.write('\015'); outstream.write('\012');
      outstream.flush();

      String result = instream.readLine();
      return result;
   };
}