java - 电子邮件应用程序中的异常

Question

在用 java 编写电子邮件应用程序时出现此异常:

javax.mail.MessagingException: Could not connect to SMTP host: mail.simsystech.com, port: 8443;
  nested exception is:
    java.net.ConnectException: Connection timed out: connect
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1934)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:638)
    at javax.mail.Service.connect(Service.java:317)

& 这是我的代码(按照本教程 link ):

          Properties properties = System.getProperties();
          properties.put("mail.smtp.starttls.enable", "true");
          properties.put("mail.transport.protocol", "smtp");
          properties.setProperty("mail.smtp.host", host);
//        properties.put("mail.smtp.port", "8443");
          properties.setProperty("mail.smtp.auth", "true");
          properties.setProperty("mail.smtp.starttls.enable", "true");

          final String user = "abc@xyz.com";
          final String password = "*****";

          Authenticator authenticator = new Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(user,password);
                }
            };


          Session session = Session.getDefaultInstance(properties,authenticator);


          try{
              MimeMessage message = new MimeMessage(session);

              message.setFrom(new InternetAddress(sid));

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

              message.setSubject(subject);

              BodyPart messageBodyPart = new MimeBodyPart();

              messageBodyPart.setText(text);

              Multipart multipart = new MimeMultipart();

              multipart.addBodyPart(messageBodyPart);


              messageBodyPart = new MimeBodyPart();
//            String filename = "file.txt";
              DataSource source = new FileDataSource(file);
              messageBodyPart.setDataHandler(new DataHandler(source));
              messageBodyPart.setFileName(file);
              multipart.addBodyPart(messageBodyPart);

              // Send the complete message parts
              message.setContent(multipart );


              // Now set the actual message
//            message.setText(text);

              // Send message
              Transport.send(message);
              System.out.println("Sent message successfully....");
           }catch (MessagingException ex) {
              ex.printStackTrace();
           }

尽管我浏览了 stackoverflow 的这些链接:1 , 2

知道为什么我会收到此错误... :( :(

Answer 1

Any idea why I'm getting this error...

两个最明显的潜在原因是:

• 您的 SMTP 主机的主机名和/或端口号有误。如果没有 SMTP 服务在使用那个端口的那个主机上运行，​​那么你将不得不使用其他东西。

• 您的计算机无法通过该端口连接到该主机，因为防火墙阻止了您的访问。