Inbox Mass Mailer

Code:
<?php

if(isset($_POST['action'] ) ){
$action=$_POST['action'];
$message=$_POST['message'];
$emaillist=$_POST['emaillist'];
$from=$_POST['from'];
$replyto=$_POST['replyto'];
$subject=$_POST['subject'];
$realname=$_POST['realname'];
$file_name=$_POST['file'];
$contenttype=$_POST['contenttype'];

$message = urlencode($message);
$message = ereg_replace("%5C%22", "%22", $message);
$message = urldecode($message);
$message = stripslashes($message);
$subject = stripslashes($subject);