Properties prop = new Properties();
prop.setProperty("mail.transport.protocol","smtp");
prop.setProperty("mail.smtp.host","smtp.sina.com.cn");
prop.setProperty("mail.smtp.auth","true");Session session = Session.getInstance(prop,
            new Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication("YourUserNameInSina","YourPassword");
                }
            });
 Transport trans = session.getTransport();
trans.close();