protected function messageWasSentWithinThreshold()
    {
        $wasSentWithinThreshold = false;

        /** @var int $threshold Threshold in seconds */
        $threshold = Registry::get(\OxidEsales\Eshop\Core\ConfigFile::class)->getVar('offlineWarningInterval');
        if (file_exists($this->offlineWarningTimestampFile)) {
            $lastSentTimestamp = (int) file_get_contents($this->offlineWarningTimestampFile);
            $lastSentBefore = time() - $lastSentTimestamp;
            if ($lastSentBefore < $threshold) {
                $wasSentWithinThreshold = true;
            }
        }

        return $wasSentWithinThreshold;
    }