JavaMail smtp properties (for STARTTLS)

Question

JavaMail specifies a bunch of properties that can be set to configure an SMTP connection. To use STARTTLS it is necessary to set the following property

mail.smtp.starttls.enable=true

Where do I specify the username/password to use the smtp service? Is it enough to specify the:

mail.smtp.user=me
mail.smtp.password=secret

Or do I have to explicitely login using the:

transport.connect(server, userName, password)

Yes, I already tried to do this and it seems that it is necessary to connect using transport.connect(..). But if yes, what are the mail.smtp.user & pass properties for? Are they not enough to use smtp with starttls?

Answer 1

Here is my sendEmail method which is using GMail smtp (JavaMail) with STARTTLS

public void sendEmail(String body, String subject, String recipient) throws MessagingException,
            UnsupportedEncodingException {
        Properties mailProps = new Properties();
        mailProps.put("mail.smtp.from", from);
        mailProps.put("mail.smtp.host", smtpHost);
        mailProps.put("mail.smtp.port", port);
        mailProps.put("mail.smtp.auth", true);
        mailProps.put("mail.smtp.socketFactory.port", port);
        mailProps.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        mailProps.put("mail.smtp.socketFactory.fallback", "false");
        mailProps.put("mail.smtp.starttls.enable", "true");

        Session mailSession = Session.getDefaultInstance(mailProps, new Authenticator() {

            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(login, password);
            }

        });

        MimeMessage message = new MimeMessage(mailSession);
        message.setFrom(new InternetAddress(from));
        String[] emails = { recipient };
        InternetAddress dests[] = new InternetAddress[emails.length];
        for (int i = 0; i < emails.length; i++) {
            dests[i] = new InternetAddress(emails[i].trim().toLowerCase());
        }
        message.setRecipients(Message.RecipientType.TO, dests);
        message.setSubject(subject, "UTF-8");
        Multipart mp = new MimeMultipart();
        MimeBodyPart mbp = new MimeBodyPart();
        mbp.setContent(body, "text/html;charset=utf-8");
        mp.addBodyPart(mbp);
        message.setContent(mp);
        message.setSentDate(new java.util.Date());

        Transport.send(message);
    }