Re: How long is the life of SendMail.class ?

I'm new with the servlet and all other wep application stuff so sorry if I
ask a wierd queston. I have next code which work fine:

package pascalpozega;

import java.util.*;
import java.io.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

/**
* msgsendsample creates a very simple text/plain message and sends it.
* <p>
* usage: <code>java msgsendsample <i>to from smtphost
true|false</i></code>
* where <i>to</i> and <i>from</i> are the destination and
* origin email addresses, respectively, and <i>smtphost</i>
* is the hostname of the machine that has the smtp server
* running. The last parameter either turns on or turns off
* debugging during sending.
*
* @author Max Spivak
*/
public class SendMail {
   static String msgText = "Hi,\nPlease - .\nJohn";
   public static boolean jelPoslan = true;
   public static String greska = "";

   public static void main(String[] args) throws Exception {
       sendMail("support@eatj.com", "johnzhang@xyax.com", "Hi", msgText);

       /*
       if (args.length != 4) {
           usage();
           System.exit(1);
       }

       System.out.println();

       String to = args[0];
       String from = args[1];
       String host = args[2];
       boolean debug = Boolean.valueOf(args[3]).booleanValue();

       // create some properties and get the default Session
       Properties props = new Properties();
       props.put("mail.smtp.host", host);
       if (debug) props.put("mail.debug", args[3]);

       Session session = Session.getDefaultInstance(props, null);
       session.setDebug(debug);

       // create a message
       Message msg = new MimeMessage(session);
       msg.setFrom(new InternetAddress(from));
       InternetAddress[] address = {new InternetAddress(args[0])};
       msg.setRecipients(Message.RecipientType.TO, address);
       msg.setSubject("JavaMail APIs Test");
       msg.setSentDate(new Date());
       // If the desired charset is known, you can use
       // setText(text, charset)
       msg.setText(msgText);

       Transport.send(msg);
        */

   }

   public static void sendMail(String to, String from, String subject,
String content) throws Exception {
       sendMail(to, from, subject, content, "localhost");
   }

   public static void sendMail(String to, String from, String subject,
String content, String host) throws Exception {
       // create some properties and get the default Session

       host = "localhost";

       Properties props = new Properties();
       props.put("mail.smtp.host", host);

       Session session = Session.getDefaultInstance(props, null);

       try {
           // create a message
           MimeMessage msg = new MimeMessage(session);
           msg.setFrom(new InternetAddress(from));
  msg.setHeader("Content-Type", "text/plain; charset=windows-1250");
           InternetAddress[] address = {new InternetAddress(to)};
           msg.setRecipients(Message.RecipientType.TO, address);
           msg.setSubject(subject,"windows-1250");
  //msg.setHeader("Content-Transfer-Encoding", "8bit");

           msg.setSentDate(new Date());
           // If the desired charset is known, you can use
           // setText(text, charset)
           //msg.setText(content,"Cp1250");
           msg.setText(content,"windows-1250");

           Transport.send(msg);
           msg = null;
       } catch (MessagingException mex) {

           System.out.println("\n--Exception handling in
msgsendsample.java");

           mex.printStackTrace();
           System.out.println();
           Exception ex = mex;
           greska = ex.toString();
           jelPoslan = false;
           ex = null;

           do {
               if (ex instanceof SendFailedException) {
                   SendFailedException sfex = (SendFailedException)ex;
                   Address[] invalid = sfex.getInvalidAddresses();
                   if (invalid != null) {
                       System.out.println(" ** Invalid Addresses");

                       if (invalid != null) {
                           for (int i = 0; i < invalid.length; i++)
                               System.out.println(" " +
invalid[i]);
                       }
                   }
                   Address[] validUnsent = sfex.getValidUnsentAddresses();
                   if (validUnsent != null) {
                       System.out.println(" ** ValidUnsent Addresses");
                       if (validUnsent != null) {
                           for (int i = 0; i < validUnsent.length; i++)
                               System.out.println(" "+validUnsent[i]);
                       }
                   }
                   Address[] validSent = sfex.getValidSentAddresses();
                   if (validSent != null) {
                       System.out.println(" ** ValidSent Addresses");
                       if (validSent != null) {
                           for (int i = 0; i < validSent.length; i++)
                               System.out.println(" "+validSent[i]);
                       }
                   }
               }
               System.out.println();
               if (ex instanceof MessagingException)
                   ex = ((MessagingException)ex).getNextException();
               else
                   ex = null;
           } while (ex != null);

       }
   }

   private static void usage() {
       System.out.println("usage: java msgsendsample <to> <from> <smtp>
true|false");
   }
}

Iif visitor enter wrong adress I got

javax.mail.SendFailedException: Sending failed; nested exception is: class
javax.mail.MessagingException: 553 5.5.4 ... Domain name required for
sender
address MARIONET.HR

and its OK, but it if I again enter right mail address I got the same
exception. How it memory wrong adress when I instance new SendMail class?

p.s.
What I need to setup so that I can experiment on my computer? So that I
don't have to upload SendMail.class every time I cahnged it.