public function renderForSubscriber($subscriber)
{
$parser = new TextParser();
$data = $this->buildTagData($subscriber);
$result = $parser->parseString($this->content_html, $data);
// Inject tracking pixel
$result = str_replace('</body>', $this->getTrackingPixelImage($subscriber) . PHP_EOL . '</body>', $result);
return $result;
}
