Java 邮件，设置回复地址不起作用

我用java写了一个小的电子邮件发送程序，它有，和地址，当客户端尝试回复邮件时，它应该能够回复地址。目前它不起作用，我的代码如下：fromtoreply-toreply-to

// File Name SendEmail.java

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

public class SendEmail
{
   public static void main(String [] args)
   {

      // Recipient's email ID needs to be mentioned.
      String to = "xyz@gmail.com";

      // Sender's email ID needs to be mentioned
      String from = "abcd@gmail.com";

      // Assuming you are sending email from localhost
      String host = "localhost";

      // Get system properties
      Properties properties = System.getProperties();
    properties.put("mail.smtp.from", "mnop@gmail.com");

      // Setup mail server
      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.
      Session session = Session.getDefaultInstance(properties);

      try{
         // Create a default MimeMessage object.
         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.
         message.addRecipient(Message.RecipientType.TO,
                                  new InternetAddress(to));

         // Set Subject: header field
         message.setSubject("This is the Subject Line!");

         // Now set the actual message
         message.setText("New Message goes here");

         // Send message
         Transport.send(message);
         System.out.println("Sent message successfully....");
      }catch (MessagingException mex) {
         mex.printStackTrace();
      }
   }
}

我使用了真正的gmail帐户。任何人都可以帮忙..？