problem in sending mail

Hi,
I have written following code:--

public static void sendMail(String empid,DataSource dataSource,String email,String req_id)throws Exception
{
        Employee emp=(Employee)getEmployeeById(dataSource,empid);
String emailMsgTxt      = "Dear Approving Officer,Emp Id"+empid+"wants your confirmation for Leave.<a href='http://localhost:84/EasyOffice/ApproveLeave.do?req_id='"+req_id+"'&emp_id='"+empid+"''>Click here </a> to Approve. Order Confirmation Message. Also include the Tracking Number.";
   String emailSubjectTxt  = "Application for Leave";
   String emailFromAddress =emp.getEmailId();
              
  // Add List of Email address to who email needs to be sent to
   String[] emailList =EmailIdSeparator(email);
 
    
  postMail(emailList,emailSubjectTxt,emailMsgTxt, emailFromAddress);
   
    
}
  public  static void  postMail( String recipients[ ], String subject,
                            String message , String from) throws MessagingException
  {
    boolean debug = false;
       String SMTP_HOST_NAME = "myhostname";
   String SMTP_AUTH_USER = "myusername";
   String SMTP_AUTH_PWD  = "mypassword";
     //Set the host smtp address
     Properties props = new Properties();
     props.put("mail.smtp.host", SMTP_HOST_NAME);
     props.put("mail.smtp.auth", "true");
        
    Session session = Session.getDefaultInstance(props,  new javax.mail.Authenticator() {
protected PasswordAuthentication getPasswordAuthentication(){
return new PasswordAuthentication("username", "pswd");
    }
    });
 
    session.setDebug(debug);
 
    // create a message
    Message msg = new MimeMessage(session);
 
    // set the from and to address
    InternetAddress addressFrom = new InternetAddress(from);
    msg.setFrom(addressFrom);
 
    InternetAddress[] addressTo = new InternetAddress[recipients.length];
    for (int i = 0; i < recipients.length; i++)
    {
        addressTo[i] = new InternetAddress(recipients[i]);
    }
    msg.setRecipients(Message.RecipientType.TO, addressTo);

// Setting the Subject and Content Type
    msg.setSubject(subject);
    msg.setContent(message, "text/plain");
    Transport.send(msg);
 
 
  } 
/**

But its giving following Exception though i have imported javax.mail.Authenticator :-
Thanks

javax.mail.Authenticator is in the main JavaMail JAR file, so please check if that is in the class path of your servlet.