protected function get_confirmation_folder() {

        if ($this->imapnamespace === null) {
            if ($this->client->queryCapability('NAMESPACE')) {
                $namespaces = $this->client->getNamespaces(array(), array('ob_return' => true));
                $this->imapnamespace = $namespaces->getNamespace('INBOX');
            } else {
                $this->imapnamespace = '';
            }
        }

        return $this->imapnamespace . self::CONFIRMATIONFOLDER;
    }