/**
 * Implements hook_mail_alter()
 */
function notify_entity_mail_alter(&$message){
  $from = "foo@bar.com";
  $message['from'] = $from;
}

$message['headers']['Return-Path'] = 'user@email.com';
  $message['headers']['Sender'] = 'user@email.com';
  $message['headers']['From'] = 'Site name';
  $message['headers']['Reply-to'] = 'user@email.com';