public function setHeaders(Swift_Mime_SimpleHeaderSet $headers)
    {
        $this->headerCanonData = '';
        // Loop through Headers
        $listHeaders = $headers->listAll();
        foreach ($listHeaders as $hName) {
            // Check if we need to ignore Header
            if (!isset($this->ignoredHeaders[strtolower($hName)])) {
                if ($headers->has($hName)) {
                    $tmp = $headers->getAll($hName);
                    foreach ($tmp as $header) {
                        if ('' != $header->getFieldBody()) {
                            $this->addHeader($header->toString());
                            $this->signedHeaders[] = $header->getFieldName();
                        }
                    }
                }
            }
        }

        return $this;
    }