Mail::trackRead

private function trackRead($html)
{
	if(!$this->trackReadLink)
	{
		return $html;
	}

	$url = $this->trackReadLink;
	if (mb_substr($url, 0, 4) !== 'http')
	{
		$url = $this->trackLinkProtocol . "://" . $this->settingServerName . $url;
	}

	$html .= '';

	return $html;
}