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, rellene todos los campos.";
    }
    else if( !validate_email(contact_email.text) )
    {
        message_status.text = "Por favor introduzca un email válido.";
    }
    else
    {
        message_status.text = "enviando...";
        
        var email_data:String = "nombre=" + contact_name.text
                       + "&email=" + contact_email.text
                       + "&teléfono=" + contact_subject.text
                       + "&mensage=" + 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 = "¡Gracias! Su mensaje ha sido enviado.";
        timer = new Timer(500);
        timer.addEventListener(TimerEvent.TIMER, on_timer);
        timer.start();
    }
    else
    {
        message_status.text = "¡Error! 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);
    }
}

<?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 = "yourname@yourdomain.com";
    $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";
    }
}
?>

<?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 = "yourname@yourdomain.com";
    $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";
    $email_body_auto_reply = "Hello $contact_name, \nThis is the auto reply message. Thank you. \n\nAdmin - http://www.flashmo.com";
    
    $extra = "From: $sender\r\n" . "Reply-To: $sender \r\n" . "X-Mailer: PHP/" . phpversion();
    $extra_auto_reply = "From: $receiver\r\n" . "Reply-To: $receiver \r\n" . "X-Mailer: PHP/" . phpversion();
    
    mail( $sender, "Auto Reply - Re: $contact_subject", $email_body_auto_reply, $extra_auto_reply );    // auto reply mail to sender

    if( mail( $receiver, "Flash Contact Form - $contact_subject", $email_body, $extra ) )
    {
        echo "success=yes";
    }
    else
    {
        echo "success=no";
    }
}
?>

Error: Error #2101: La cadena transmitida a URLVariables.decode() debe ser una cadena de consulta con formato URL codificado y pares nombre/valor.
    at Error$/throwError()
    at flash.net::URLVariables/decode()
    at flash.net::URLVariables()
    at flashmo_189_reflection_fla::contactform_25/receive_response()
    at flash.events::EventDispatcher/dispatchEventFunction()
    at flash.events::EventDispatcher/dispatchEvent()
    at flash.net::URLLoader/onComplete()