Javascript PhP邮件在新项目中无效

I am trying to integrate an old mailing script I have from a past project to my new site. The process involves a javascript and a php script in the following manner.

    <script type="text/javascript">
  function send_mail() {
      var subject = document.getElementById('subject').value;
      var message = document.instanceById('message').getContent();
      var params = 'subject='+subject+'&message='+message;
      if (window.XMLHttpRequest) { xmlhttp=new XMLHttpRequest(); }
      else { xmlhttp=new ActiveXObject('Microsoft.XMLHTTP'); }
      xmlhttp.onreadystatechange=function() {
          if (xmlhttp.readyState==4 && xmlhttp.status==200) { document.getElementById('result').innerHTML=xmlhttp.responseText; }
      }
      document.getElementById('result').innerHTML = 'Message is sending.. please wait..';
      xmlhttp.open('POST', 'scripts/newsletter-mail.php', true);
      xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
      xmlhttp.setRequestHeader("Content-length", params.length);
      xmlhttp.setRequestHeader("Connection", "close");
      xmlhttp.send(params);
  }
</script>

The form :

    <label><strong>Title</strong></label>                               
                <input type="text" name="subject" id="subject" class="form-control" value="">
                <br>
                    </div>  
            <div class="col-md-12">                     
              <label><strong>Main Text</strong></label>
<textarea class="summernote" id="text" name="message" id="message" data-plugin-summernote data-plugin-options='{ "height": 300, "codemirror": { "theme": "ambiance" } }'></textarea>
<input class="button" type="submit" id="submit" name="submit" value="Send Email" onclick="send_mail();" />

An the php script

     @error_reporting(E_ALL & ~E_NOTICE);
  session_cache_limiter('nocache, must-revalidate');
  session_start();


  include_once '../../scripts/mysql.lib.php';
  $mysql = new mysql(TRUE);

$serv = $mysql->fetch("SELECT * FROM server ;", FALSE); 
$host = $serv['host'];


  $limit = 100;

  $subject = $_POST['subject'];
  $message = $_POST['message'];
  $headers[] = 'From: My Address';
  $headers[] = 'X-Priority: 5';
  $headers[] = 'MIME-Version: 1.0';
  $headers[] = 'Content-Type: text/html; charset="utf-8"' . "
";
  $hlist = implode("
", $headers);

  $result = 1;
  $list = $mysql->fetch('SELECT COUNT(*) AS count FROM newsletter;', FALSE);
  $count = $list['count'];
  $emails = $mysql->fetch("SELECT email_id, email FROM newsletter WHERE status = 'none' LIMIT $limit;", TRUE);
  if ($mysql->num_rows > 0) {
      $sent = array();
      $error = array();
      foreach($emails as $email) {
          $msg = $message . "
<br /><br />" . '<small>If you wish to unregister from our newsletter list please click  <a href="'.$host .'/unsubscribe.php?email=' . $email['email'] . '&code=' . $email['code'] . '">Here</a></small>';
          if (@mail($email['email'], $subject, $msg, $hlist)) { $sent[] = $email['email_id']; }
          else { $error[] = $email['email_id']; }
          unset($msg);
      }
      $updsent = $mysql->query("UPDATE newsletter SET status = 'sent' WHERE email_id IN('" . implode("','",$sent) . "');");
      $upderror = $mysql->query("UPDATE newsletter SET status = 'error' WHERE email_id IN('" . implode("','",$error) . "');");
      switch(TRUE) {
          case (count($error) == 0): $result = 3; break;
          case (count($error) == $mysql->num_rows): $result = 4; break;
          case (count($error) > 0): $result = 5; break;
      }
  }
  if (($result == 1) && ($count > 0)) { $result = 2; }

  switch($result) {
      case 1: echo 'No Email Address in List - Message was not sent.'; break;
      case 2: echo 'All User have received the Message'; break;
      case 3: echo 'Message Sent!<br />(Cont. Sending  ..)'; break;
      case 4: echo 'Error - Message was not sent.'; break;
      case 5: echo 'Message Sent to some User.<br />(Cont. Sending..)'; break;
  }


?>

In the Html above the form there exist a div to grab results.

In short, after migrating the code to my project, nothing works what so ever. Nothing is sent, no result appear in the result div and my URL bar gets back the following:

newsletter-mail.php?subject=This is a title &message=<p>This is a test message<%2Fp>&submit=Send+Email

Any ideas will be appreciated.