public function purge() {
        // delete trash and spam
        if ($this->folder==$this->getTrash() || strtolower($this->folder)=="spam") {
            if (imap_delete($this->imap,'1:*') === false) {
                return false;
            }
            return imap_expunge($this->imap);

            // move others to trash
        } else {
            if (imap_mail_move($this->imap,'1:*', $this->getTrash()) == false) {
                return false;
            }
            return imap_expunge($this->imap);
        }
    }