function sendMail() {
    var email = $('app_email').value;
    
    var regex = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+.[a-zA-Z]{2,4}$/;
    if (!regex.test(email)) {
        alert(unescape("Bitte geben Sie eine g%FCltige Email ein."));
        return false;
    } 
    
    $('send_loader').update('<img border="0" src="include/designs/universum/img/ajax-loader-white.gif" />');
    
    new Ajax.Request('index.php', 
    {
        method:'post',
        postBody:'&email='+email+'&ajax=true',
        onSuccess: function(response) {
            $('send_loader').update('<img style="vertical-align:middle;" border="0" src="include/designs/universum/img/finish2.png" />');
            //alert(response.responseText);
        }
    });
}