var smtp = nodemailer.createTransport({
    host: 'mail.privateemail.com',
    port: 25,
    auth: {
        user: 'contact@myemail.com',
        pass: 'mypassword'
    }
});

Outgoing server (SMTP): port 465 for SSL, port 587 for TLS/STARTTLS

Outgoing server authentication should be switched on,
SPA (secure password authentication) must be disabled.