我写的JavaMail代码，可以用163免费邮箱发邮件，却不能用163免费企业邮箱发送

            String host = "smtp.ym.163.com"; // 163免费企业邮箱的smtp服务器

		String from = "myname@****.com"; // 我的企业邮箱地址

		String to = "receiver@***.com"; // 邮件要发送到的邮箱地址

		String username = "myname@****.com"; 

											

		String password = "secret"; //



		Properties props = new Properties();



		

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

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



		SmtpAuth smtpAuth = new SmtpAuth(username, password);

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

		

		

		session.setDebug(true);



		String msg = "hello";

		MimeMessage message = new MimeMessage(session);

		message.setFrom(new InternetAddress(from));

		message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

		BodyPart mdp = new MimeBodyPart();

		mdp.setContent(msg, "text/html;charset=gb2312");

		Multipart mm = new MimeMultipart();

		mm.addBodyPart(mdp);

		message.setContent(mm);



		message.setSubject("这是一个好消息");

		message.saveChanges();

		Transport transport = session.getTransport("smtp");

		transport.connect(host, username, password);

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

		transport.close();