title: mail is not send when the create new user and notify that user
body: <p>I have made site using drupal-7 there is the one issue i m facing is that,
  When i m create new user i m check the checkbox notify user but the email is not send and message is come like
   Unable to send e-mail. Contact the site administrator if the problem persists.</p>
  
  <p>i can not understand where the actual problem is</p>
  
  <p>Thank in advance</p>