title: Error sending to the following VALID addresses Jenkins when Email id is correct?
body: <pre><code>Checking for pre-build
  Executing pre-build step
  Checking if email needs to be generated
  Email was triggered for: Before Build
  Sending email for trigger: Before Build
  messageContentType = text/html; charset=UTF-8
  Request made to attach build log
  Adding recipients from project recipient list
  Adding recipients from trigger recipient list
  Successfully created MimeMessage
  Sending email to: chandra.ganpathy@*****.com
  Error sending to the following VALID addresses: chandra.ganpathy@*****.com
  SendFailedException message: 501 5.1.7 Invalid address
  </code></pre>
  
  <p>This email id is correct which is configured in Editable Email Notification.. Why I am getting this error?</p>