private function get_thread_row($mailbox)
    {
        // Get thread from DB
        $sql_result = $this->db->query(
            "SELECT `data`"
            ." FROM {$this->thread_table}"
            ." WHERE `user_id` = ?"
                ." AND `mailbox` = ?",
            $this->userid, $mailbox);

        if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
            $data   = explode('@', $sql_arr['data']);
            $thread = $this->db->decode($data[0], true);
            unset($data[0]);

            if (empty($thread)) {
                $thread = new rcube_result_thread($mailbox);
            }

            return array(
                'object'   => $thread,
                'deleted'  => $data[1],
                'validity' => $data[2],
                'uidnext'  => $data[3],
            );
        }

        return null;
    }