JavaMail through Exchange server with SSO Authentication

Question

I've seen several posts that offer a solution to something very similar to my situation but for whatever reason it does not work for me.

For example, here it's presented as a working sample illustrating OP's related problem and here as an actual answer.

I need to send e-mail as myself from my Exchange account via SMTP using SSO UserID and Password. This all happens in a restricted corporate environment.

From what I understand from the debug info I'm successfully connecting to an SMTP server and then fail user authentication with 530 5.7.1 Client was not authenticated. NTLM authentication itself seems to be enabled.

DEBUG:

DEBUG: setDebug: JavaMail version 1.5.4
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Oracle]
DEBUG SMTP: useEhlo true, useAuth false
DEBUG SMTP: trying to connect to host "server.bank.com", port 25, isSSL false
220 server1.corp.bank.com Microsoft ESMTP MAIL Service ready at Mon, 24 Aug 2015 17:15:24 -0400
DEBUG SMTP: connected to host "server.bank.com", port: 25

EHLO server2.corp.bank.com
250-server1.corp.bank.com Hello [xxx.xxx.xxx.xxx]
250-SIZE
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-X-ANONYMOUSTLS
250-AUTH NTLM LOGIN
250-X-EXPS GSSAPI NTLM
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250-XEXCH50
250-XRDST
250 XSHADOW
DEBUG SMTP: Found extension "SIZE", arg ""
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "DSN", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "X-ANONYMOUSTLS", arg ""
DEBUG SMTP: Found extension "AUTH", arg "NTLM LOGIN"
DEBUG SMTP: Found extension "X-EXPS", arg "GSSAPI NTLM"
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "BINARYMIME", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "XEXCH50", arg ""
DEBUG SMTP: Found extension "XRDST", arg ""
DEBUG SMTP: Found extension "XSHADOW", arg ""
DEBUG SMTP: use8bit false
MAIL FROM:<first.last@bank.com>
530 5.7.1 Client was not authenticated
DEBUG SMTP: got response code 530, with response: 530 5.7.1 Client was not authenticated

Essential part of my code:

static void sendEmail(){

    Properties props = System.getProperties();
    props.setProperty("mail.smtp.host", host);
    props.setProperty("mail.smtp.port", "25");
    // props.setProperty("mail.debug", "true");
    // props.setProperty("mail.debug.auth", "true");
    props.setProperty("mail.smtp.starttls.enable","true");
    props.setProperty("mail.smtp.auth.mechanisms", "NTLM");
    props.setProperty("mail.smtp.auth.ntlm.domain", user_sso_domain);

    // Session session = Session.getDefaultInstance(props);
    Session session = Session.getDefaultInstance(props,
            new javax.mail.Authenticator() {
                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(user_sso_id, user_sso_password);
                }
            });
    session.setDebug(true);

    try {
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(email_from));
        message.addRecipient(Message.RecipientType.TO,
                new InternetAddress(email_to));
        message.setSubject("Test Message");
        message.setText("This is my test message");
        Transport.send(message);

    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

I would appreciate your suggestions for further troubleshooting.

EDIT

Working code after implementing the fix and better practices from the accepted answer:

private static void sendEmail(){

    Properties props = System.getProperties();
    props.setProperty("mail.smtp.host", host);
    props.setProperty("mail.smtp.port", "25");
    // props.setProperty("mail.debug", "true");
    // props.setProperty("mail.debug.auth", "true");
    props.setProperty("mail.smtp.auth", "true");
    props.setProperty("mail.smtp.starttls.enable","true");
    props.setProperty("mail.smtp.auth.mechanisms", "NTLM");
    props.setProperty("mail.smtp.auth.ntlm.domain", user_sso_domain);

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

    try {
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(email_from));
        message.addRecipient(Message.RecipientType.TO,
                new InternetAddress(email_to));
        message.setSubject("Test Message");
        message.setText("This is my test message");
        Transport.send(message, user_sso_id, user_sso_password);

    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

Answer 1

You need to set "mail.smtp.auth" to "true".

Or, better yet, fix these common mistakes and make your program much simpler.