JavaMail API to iMail -- java.net.SocketException: Permission denied: connect

Question

I am having trouble getting an application to use the JavaMail API to send out some files in a more automated way than we are used to doing. I am very new to Java and NetBeans, but have programmed in other languages, so please forgive me if I seem a little lost to Java and or NetBeans.

I keep getting this error

java.net.SocketException: Permission denied: connect

when trying to connect to the local mail server. I have connected and sent mail successfully through gmail's SMTP server with the same code, just changing username, password, and port. I was also able to telnet to our server successfully and get a 220 response from port 25. I also have a batch file that runs and it successfully sends e-mail through our local server. Any thoughts or ideas as to why I can't connect through JavaMail?

Here is the code that sends the e-mail.

Source code:

public void sendEmail(String customerNumber, ArrayList fileList){
   String from = "xxxx";
   String username = "xxxx";
   String to = "xxxx";
   String host = "10.1.1.6";
   String pwd = "xxxx";
   String port = "25";

   Properties props = System.getProperties();
   props.put("mail.smtp.host", host);
   props.put("mail.smtp.port", port);
   props.put("mail.smtp.user", username);
   props.put("mail.smtp.auth", "true");
   props.put("mail.smtp.starttls.enable", "true");
   props.put("mail.smtp.debug", "true");
   props.put("mail.smtp.socketFactory.port", port);
   props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
   props.put("mail.smtp.socketFactory.fallback", "false");

   Session session = Session.getInstance(props, null);
   session.setDebug(true);

   MimeMessage message = new MimeMessage(session);
   try{
       message.setFrom(new InternetAddress(from));
       message.setRecipients(Message.RecipientType.TO, to);
       message.setSubject("Electronic Invoices");
       BodyPart messageBodyPart = new MimeBodyPart();
       messageBodyPart.setText("Electronic Invoices");
       Multipart multipart = new MimeMultipart();
       multipart.addBodyPart(messageBodyPart);
       for(int i = 0; i < fileList.size(); i++){
           messageBodyPart = new MimeBodyPart();
           String fileName = (String) fileList.get(i);
           DataSource source = new FileDataSource(fileName);
           messageBodyPart.setDataHandler(new DataHandler(source));
           messageBodyPart.setFileName(fileName);
           multipart.addBodyPart(messageBodyPart);
       }
       message.setContent(multipart);

       Transport tr;
       tr = session.getTransport("smtp");
       tr.connect(host, username, pwd);
       tr.sendMessage(message, message.getAllRecipients());
       jTextArea2.append("Mail Sent Successfully");
       tr.close();

   } catch(Exception e){
       jTextArea2.append("sendEmail()::" + System.getProperty("line.separator") + e + System.getProperty("line.separator"));
       System.out.println(e.getMessage());
       System.out.println(e.getCause());
   }
}

Output from the two Exception statements:

DEBUG: setDebug: JavaMail version 1.4.5
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "10.1.1.6", port 25, isSSL false
Could not connect to SMTP host: 10.1.1.6, port: 25
java.net.SocketException: Permission denied: connect

Answer 1

Add -Djava.net.preferIPv4Stack=true to the VM options. Another way to confirm if it is the same issue, in Netbeans, right click on the project > properties > Libraries and choose a JDK 6 Java Platform (install if you do not have it). Clean, build then try again. This will eliminate this issue as the problem

Credit https://stackoverflow.com/a/7478027/643500

Answer 2

In case to simplify app invocation (e.g. from CLI) used in the code at start:

System.setProperty("java.net.preferIPv4Stack", "true")

supposing that the app will be working with legacy IPv4 network stack.