网上很多，不过一般都是没有smtp验证的，下边是一段示例代码：
  不能直接运行的，不过，可以看看里面关于验证的部分。

  //发送邮件函数
  public boolean sendMail(String mailTo,String mailSubject,String mailBody){
    //发送email
    try {
      //default account information
      String smtpServer = "smtp.smtpserver.com";
      String smtpAuth = "true";
      String smtpUser = "username";
      String smtpPassword = "password";
      String From = "from@yourserver.com";
      String To = mailTo;
      String Subject = mailSubject;
      String Text = mailBody;
      java.util.ResourceBundle resBundle;
      resBundle = java.util.ResourceBundle.getBundle("mailinfo",
          Locale.SIMPLIFIED_CHINESE);
      if (resBundle != null) {
        smtpServer = resBundle.getString("mail.smtp.host");
        smtpAuth = resBundle.getString("mail.smtp.auth");
        smtpUser = resBundle.getString("mail.smtp.user");
        smtpPassword = resBundle.getString("mail.smtp.password");
        From = resBundle.getString("mail.smtp.from");
      }
      Properties props = new Properties();
      Session sendMailSession;
      Transport transport;
      props.put("mail.smtp.host", smtpServer);
      props.put("mail.smtp.auth", smtpAuth);
      if ("true".equals(smtpAuth)) {
        //smtp服务器需要验证，用MyAuthertiactor来创建mail session
        MyAuthenticator myauth = new MyAuthenticator(smtpUser, smtpPassword);
        sendMailSession = Session.getInstance(props, myauth);
      }
      else {
        sendMailSession = Session.getInstance(props);
      }
      //Debug
      sendMailSession.setDebug(true);
      Message newMessage = new MimeMessage(sendMailSession);
      newMessage.setFrom(new InternetAddress(From));
      newMessage.setRecipient(Message.RecipientType.TO,
                              new InternetAddress(mailTo));
      newMessage.setSubject(Subject);
      newMessage.setSentDate(new Date());
      newMessage.setText(Text);
      newMessage.saveChanges();
      transport = sendMailSession.getTransport("smtp");
      transport.send(newMessage, newMessage.getAllRecipients());
      transport.close();
    }
    catch (Exception mailEx) {
      System.err.println("Send Mail Error:" + mailEx.getMessage());
      return false;
    }
    return true;
  }

  //smtp需要验证时候的验证类
  class MyAuthenticator
      extends javax.mail.Authenticator {
    private String strUser;
    private String strPwd;
    public MyAuthenticator(String user, String password) {
      this.strUser = user;
      this.strPwd = password;
    }

    protected PasswordAuthentication getPasswordAuthentication() {
      return new PasswordAuthentication(strUser, strPwd);
    }
  }