title: Nodemailer Missing credentials for "PLAIN"
body: <p>Nodemailer was working correctly for a few months with exactly the same configuration.</p>
  
  <p><code>var smtpTransport = nodemailer.createTransport({
       service: "Zoho",
       auth: {
           user: environment.smtp.email,
           password: environment.smtp.password
       },
       secure: false,
       tls: {
         rejectUnauthorized: false
       }
   });
  </code></p>
  
  <p><code>var mailOptions = {
        from: environment.smtp.email,
        to: 'some@email.com', 
        subject: 'Subject',
        html: "Mail content here."
    }</code></p>
  
  <p><code>smtpTransport.sendMail(mailOptions, function(error, response){
       console.log(error)
    });</code></p>
  
  <p>It throw " Missing credentials for "PLAIN" ". I have used this config in many places in the app and now it throw this error everywhere. But was working well when I have write the code first time.</p>
  
  <blockquote>
    <p>"nodemailer": "^4.0.1"</p>
  </blockquote>