No recibo los mails enviados desde mi página web

He bajado un flash template para mi página web. El formulario que llenan mis visitantes registran que el mail se envío exitosamente pero yo nunca los recibo en mi casilla, les remito los archivos PHP y flash
Archivo PHP
<?php
$contact_name = $_POST['name'];
$contact_email = $_POST['email'];
$contact_subject = $_POST['subject'];
$contact_message = $_POST['message'];
if( $contact_name == true )
{
 $sender = $contact_email;
 $receiver = "[email protected]";
 $client_ip = $_SERVER['REMOTE_ADDR'];
 $email_body = "Name: $contact_name \nEmail: $sender \n\nSubject: $contact_subject \n\nMessage: \n\n$contact_message \n\nIP: $client_ip \n\nFlash Contact Form provided by http://www.flashmo.com";  
 $extra = "From: $sender\r\n" . "Reply-To: $sender \r\n" . "X-Mailer: PHP/" . Phpversion();
 if( mail( $receiver, "Flash Contact Form - $contact_subject", $email_body, $extra ) )
 {
  echo "success=yes";
 }
 else
 {
  echo "success=no";
 }
}
?>
Archivo FLASH
contact_name.text = contact_email.text = contact_subject.text =
contact_message.text = message_status.text = "";
send_button.addEventListener(MouseEvent.CLICK, submit);
reset_button.addEventListener(MouseEvent.CLICK, reset);
var timer:Timer;
var var_load:URLLoader = new URLLoader;
var URL_request:URLRequest = new URLRequest( "send_email.php" );
URL_request.method = URLRequestMethod.POST;
function submit(e:MouseEvent):void
{
 if( contact_name.text == "" || contact_email.text == "" ||
  contact_subject.text == "" || contact_message.text == "" )
 {
  message_status.text = "* Por favor complete todos los campos.";
 }
 else if( !validate_email(contact_email.text) )
 {
  message_status.text = "* Por favor ingrese un mail válido.";
 }
 else
 {
  message_status.text = "enviando...";
  var email_data:String = "name=" + contact_name.text
        + "&email=" + contact_email.text
        + "&subject=" + contact_subject.text
        + "&message=" + contact_message.text;
  var URL_vars:URLVariables = new URLVariables(email_data);
  URL_vars.dataFormat = URLLoaderDataFormat.TEXT;
  URL_request.data = URL_vars;
  var_load.load( URL_request );
  var_load.addEventListener(Event.COMPLETE, receive_response );
 }
}
function reset(e:MouseEvent):void
{
 contact_name.text = contact_email.text = contact_subject.text =
 contact_message.text = message_status.text = "";
}
function validate_email(s:String):Boolean
{
 var p:RegExp = /(\w|[_.\-])+@((\w|-)+\.)+\w{2,4}+/;
 var r:Object = p.exec(s);
 if( r == null )
 {
  return false;
 }
 return true;
}
function receive_response(e:Event):void
{
 var loader:URLLoader = URLLoader(e.target);
    var email_status = new URLVariables(loader.data).success;
 if( email_status == "yes" )
 {
  message_status.text = "Su mensaje fue enviado correctamente.";
  timer = new Timer(500);
  timer.addEventListener(TimerEvent.TIMER, on_timer);
  timer.start();
 }
 else
 {
  message_status.text = "Su mensaje no se ha podido enviar.";
 }
}
function on_timer(te:TimerEvent):void
{
 if( timer.currentCount >= 10 )
 {
  contact_name.text = contact_email.text = contact_subject.text =
  contact_message.text = message_status.text = "";
  timer.removeEventListener(TimerEvent.TIMER, on_timer);
 }
}