初学者; javamail编写的smtp发送邮件小程序，向163发送邮件失败 求救

[hai22yu23]

我用此小程序发送邮件到sohu是可以发送成功的，但是向163发送时却遇到这样的错误提示：
553 Requested action not taken: Local user only,smtp1,wKjRC7Dr+AGpORxGgCA5FA==.12289S2 1176254
请问是什么原因？
如果是因为身份验证的原因的话，我已经加入身份验证的部分了
源程序如下：
import javax.mail.*;
import javax.mail.internet.*;
import java.util.*;
import javax.mail.Authenticator;
import java.io.*;

public class SimpleSmtpClient
{
String smtpServer;
String to;
String from;
String subject;
String body;
String username;
String password;

public SimpleSmtpClient(){
setup();
log("Constructor complete");
}
private void setup()
{
smtpServer="smtp.163.com";
to="[e-mail]";
from="[e-mail]";
subject="Unleased book example";
body="This is a test to see if we can send a messge/double test ";
username="50971231";
password="*******";
log("setup completed");
}
private void send()
{
try{
log("Sending a message to "+to);
Properties props=System.getProperties();

props.put("mail.smtp.host",smtpServer);
props.put("mail.smtp.user","50971231");
props.put("mail.debug","true");
StupidAuthenticator sa=new StupidAuthenticator();
Session session =Session.getDefaultInstance(props,sa);

Message msg=new MimeMessage(session);

msg.setFrom(new InternetAddress(from));
msg.setRecipients(Message.RecipientType.TO,InternetAddress.parse(to,false));

msg.setSubject(subject);
msg.setText(body);

msg.setSentDate(new Date());
Transport transport =session.getTransport("smtp");
transport.connect(smtpServer,username,password);
transport.sendMessage(msg,msg.getAllRecipients());
transport.close();


System.out.println("Message was sent");

}catch(Exception e)
{
log("Error sending message"+e);
}
}


private void log(String s)
{
System.out.println(s);

}

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

sc.send();

System.out.println("SimleSmtpClient is done");
}
}

[最牛傻蛋]

应该是本地用户才能发送吧

[umbrella1984]

smtpServer="smtp.163.com";
to="[e-mail]";

props.put("mail.smtp.host",smtpServer);
props.put("mail.smtp.user","50971231");

不能自己给自己发信