function ff_validemail_or_empty(element, message)
{
    if(element.value != '') {
        var check =
        /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
        if (!check.test(element.value)){
            if (message=='') message = element.name+" is no valid email address.\n";
            ff_validationFocus(element.name);
            return message;
        } // if
    } // if
    return '';
} // ff_validemail_or_empty