protected function StockWasUpdatedHook($dOldValue, $dNewValue)
    {
        $bReturn = parent::StockWasUpdatedHook($dOldValue, $dNewValue);
        if ($dOldValue < 1 && $dNewValue > 0) {
            $oShopArticlePreorderList = &TdbPkgShopArticlePreorderList::GetListForShopArticleId($this->id);
            while ($oShopArticlePreorder = $oShopArticlePreorderList->Next()) {
                $oShopArticlePreorder->SendMail();
            }
        }

        return $bReturn;
    }