AS3 to PHP - mail() function

当我点击发送时，文本框显示"正在发送……"没有变化。我确信这以前是有效的，但客户注意到它最近不起作用。我找不到问题，请帮忙。

我有这个AS3 的swf

var var_load:URLLoader = new URLLoader;  
var URL_request:URLRequest = new URLRequest( "http://www.blah.com/send_email_auto_response.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 = "Please fill up all text fields.";  
    }  
    else if( !validate_email(contact_email.text) )  
    {  
        message_status.text = "Please enter the valid email address.";  
    }
    else  
    {  
        message_status.text = "sending...";     
        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 );
    }  
}  

调用带有此PHP代码的页面。。

$contact_name = $_POST['name'];    
$contact_email = $_POST['email'];    
$contact_subject = $_POST['subject'];  
$contact_message = $_POST['message'];  
if( $contact_name == true )  
{  
    $sender = $contact_email;  
    $receiver = "info@blah.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'n";  
    $email_body_auto_reply = "Hello $contact_name, 'nThis is the auto reply message. Thank you.";  
    $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";
    }
}