function attach_public_key(&$message)
    {
        $headers = $message->headers();
        $from    = rcube_mime::decode_address_list($headers['From'], 1, false, null, true);
        $from    = $from[1];

        // find my key
        if ($from && ($key = $this->find_key($from, true))) {
            $pubkey_armor = $this->export_key($key->id);

            if (!$pubkey_armor instanceof enigma_error) {
                $pubkey_name = '0x' . enigma_key::format_id($key->id) . '.asc';
                $message->addAttachment($pubkey_armor, 'application/pgp-keys', $pubkey_name, false, '7bit');
                return true;
            }
        }

        return false;
    }