为什么javamail发送失败？？？
前几次还能发送成功,但是后来一次都不行了

public class MailUtil {



    static int port = 587;



    static String server = "smtp.qq.com";//邮件服务器mail.cpip.net.cn



    static String from = "张三";//发送者,显示的发件人名字



    static String user = "邮箱地址";//发送者邮箱地址



    static String password = "**************";//密码



   

    public static void sendEmail(String email, String subject, String body) throws UnsupportedEncodingException {

        try {

            Properties props = new Properties();

            props.put("mail.smtp.host",server);

            props.put("mail.smtp.port","465");

            props.put("mail.smtp.auth","true"); 

            Transport transport = null;

            Session session = Session.getDefaultInstance(props, null);

            transport = session.getTransport("smtp");

            transport.connect(server, user, password);

            MimeMessage msg = new MimeMessage(session);

            msg.setSentDate(new Date());

            InternetAddress fromAddress = new InternetAddress(user,from,"UTF-8");

            msg.setFrom(fromAddress);

            InternetAddress[] toAddress = new InternetAddress[1];

            toAddress[0] = new InternetAddress(email);

            msg.setRecipients(Message.RecipientType.TO, toAddress);

            msg.setSubject(subject, "UTF-8");   

            msg.setText(body, "UTF-8");

            msg.saveChanges();

            transport.sendMessage(msg, msg.getAllRecipients());

            transport.close();

        } catch (NoSuchProviderException e) {

            e.printStackTrace();

        } catch (MessagingException e) {

            e.printStackTrace();

        }

    }

    public static void main(String args[]) throws UnsupportedEncodingException

    {



        sendEmail("2105616491@qq.com","淫荡的人","猥琐！！");//收件人

        System.out.println("ok");

    }

这是错误代码


ok
javax.mail.AuthenticationFailedException: 530 Error: A secure connection is requiered(such as ssl). More information at http://service.mail.qq.com/cgi-bin/help?id=28

at com.sun.mail.smtp.SMTPTransport$Authenticator.authenticate(SMTPTransport.java:826)
at com.sun.mail.smtp.SMTPTransport.authenticate(SMTPTransport.java:761)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:685)
at javax.mail.Service.connect(Service.java:295)
at javax.mail.Service.connect(Service.java:176)
at com.javaMail.entity.MailUtil.sendEmail(MailUtil.java:38)
at com.javaMail.entity.MailUtil.main(MailUtil.java:60)



跪求高手！！！！
------解决方案--------------------
试了下
 smtp.qq.com   改成 smtp.exmail.qq.com  就好了