pbootcms留言过滤垃圾留言

如何给pbootcms添加垃圾留言过滤的功能？

app/home/MessageController.php  84行添加下面代码

$arr = array("http","www","baidu","google","seo","优化","排名","百度","websites");
foreach($arr as $key)
 {
   if(strpos($mail_body,$key) > 0){
  alert_back('请勿提交推销内容! \\n ERROR! \\n Reject the promotion, \\n please check the content before submitting!');
                                                }
  }