TLS issue when sending to gmail through JavaMail

Question

Turns out that JavaMail is a bit more frustrating than I thought it would be. I've looked at several examples online on how to send a simple SMTP email through Gmail's servers (but not through SSL). After trying several different examples of code, I keep concluding to the same example exception when I call transport.connect(). I keep getting this stack trace:

Exception in thread "main" com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first. l10sm302158wfk.21
     at com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:2057)
     at com.sun.mail.smtp.SMTPTransport.mailFrom(SMTPTransport.java:1580)
     at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:1097)
     at SendEmail.main(SendEmail.java:47)

Can someone please tell me what I should add or do to fix this?

Here is my code:

    Properties props = new Properties();
    props.put("mail.transport.protocol", "smtp");
    props.put("mail.host", "smtp.gmail.com");
    props.put("mail.user", "blahblah@gmail.com");
    props.put("mail.password", "blah");
    props.put("mail.port", "587");

    Session mailSession = Session.getDefaultInstance(props, null);
    Transport transport = mailSession.getTransport();

    MimeMessage message = new MimeMessage(mailSession);
    message.setSubject("This is a test");
    message.setContent("This is a test", "text/plain");
    message.addRecipient(Message.RecipientType.TO, new InternetAddress("blahblah2@gmail.com"));

    transport.connect();
    transport.sendMessage(message, message.getRecipients(Message.RecipientType.TO));
    transport.close();

Answer 1

You need to enable STARTTLS. Add one more property to your configuration:

props.put("mail.smtp.starttls.enable", "true");

Answer 2

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

public class CopyOfSendMail {

private static String SMPT_HOSTNAME = "my smtp port no";
private static String USERNAME = "root";
private static String PASSWORD = "root";

public static void main(String[] args) {
    Properties props = new Properties();
    props.put("mail.smtp.host", SMPT_HOSTNAME);
    props.put("mail.from","aaa@gmail.com");
    props.put("mail.smtp.starttls.enable", "true");
    props.put("mail.smtp.auth", "true");
    props.put("mail.debug", "true");

    Session session = Session.getInstance(props, new Authenticator() {
        @Override
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(USERNAME, PASSWORD);
        }
    });
    try {
        MimeMessage msg = new MimeMessage(session);
        msg.setFrom();
        msg.setRecipients(Message.RecipientType.TO,
                          "bbb@gmail.com");
        msg.setSubject("JavaMail hello world example");
        msg.setSentDate(new Date());
        msg.setText("Hello, world!\n");
        Transport.send(msg);
     } catch (MessagingException mex) {
        System.out.println("send failed, exception: " + mex);
     }
    }
}

Answer 3

Here Mail Sender which is using MSN-SMTP service

My host is smtp.live.com and port is 587.

As given in official doc of Java Mail, here you can get more info about best Java Mail mechanism to send and receive mails.

Properties of Mail Client are:

  Properties mailProps = new Properties();
  mailProps.put("mail.smtp.user",mailID);
  mailProps.put("mail.smtp.host",host);
  mailProps.put("mail.smtp.auth", "true");
  mailProps.put("mail.smtp.port",port);
  mailProps.put("mail.smtp.starttls.enable", "true");
  Session mailSession = Session.getInstance(mailProps,null);

Sending mechanism is :

 SMTPTransport t=(SMTPTransport)mailSession.getTransport("smtp");
 System.out.println(" Taking protocol! ");
 t.connect(host, mailID, password);
 System.out.println(" Connection Successfull! ");
 t.sendMessage(mimMessage,mimMessage.getAllRecipients());

Note:
Code is running well on local Indian Server. But this is not responding at Azur Congo: Both are Linux server.

Error is:

 com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first

Even if system property set manually:

 java -Dmail.smtp.starttls.enable=true SendAMai

also @Rob Harrop and @Brian 's points are ensured

if you're on Linux ensure that you have libnss3 and openssl installed