/** * @param Parser $parser * @return array */ private static function getHeadersRelevantForMailerDetectionEml(Parser &$parser) { return self::filterHeaders(['x-mailer' => $parser->getHeader('x-mailer'), 'message-id' => $parser->getHeader('message-id'), 'received' => $parser->getHeader('received'), 'mime-version' => $parser->getHeader('mime-version'), 'user-agent' => $parser->getHeader('user-agent')]); }