Sending mail error, javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;

Question

Here is my code

import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;


public class MailSendClass {
    public static void main (String [] args){

      // Recipient's email ID needs to be mentioned.
      String to = "[email protected]";

      // Sender's email ID needs to be mentioned
      String from = "[email protected]";

      // Assuming you are sending email from localhost
      String host = "localhost";

      // Get system properties
      Properties properties = System.getProperties();

      // Setup mail server
      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.
      Session session = Session.getDefaultInstance(properties);

      try{
         // Create a default MimeMessage object.
         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.
         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

         // Set Subject: header field
         message.setSubject("Thanks for registering on our website!");

         // Now set the actual message
         message.setText("Welcome To Job Portal !!!!  Again Thanks ");

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

    }
}

And I am getting this error everytime

javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;
  nested exception is:
    java.net.ConnectException: Connection refused: connect
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1706)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:525)
    at javax.mail.Service.connect(Service.java:291)
    at javax.mail.Service.connect(Service.java:172)
    at javax.mail.Service.connect(Service.java:121)
    at javax.mail.Transport.send0(Transport.java:190)
    at javax.mail.Transport.send(Transport.java:120)
    at MailSendClass.main(MailSendClass.java:58)
Caused by: java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at java.net.Socket.connect(Socket.java:538)
    at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:284)
    at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:227)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1672)
    ... 7 more
BUILD SUCCESSFUL (total time: 3 seconds)

I am not getting the error why this is happening. Please help me in fixing this error.

Answer 1

Error is self explainatory: javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;

You have no SMTP server on localhost, but you configure it there :

  // Assuming you are sending email from localhost
  String host = "localhost";
  ...
  // Setup mail server
  properties.setProperty("mail.smtp.host", host);

So you must:

• either configure a local SMTP server as a relay on your local system (Postfix or sendmail are two well knows servers)
• of configure a dummy server that simply traces the mail request but does not even try to deliver mail (Python is known to have such dummy servers out of the box)
• or configure your application with a server that you are allowed to use - contact your system admin in a corporate environment, or your ISP in an individual one. Anyway, you will need that even to configure a true relay.