checkQuota example

     // not yet * @param string|Zend_Mail_Message|Zend_Mime_Message $message message as string or instance of message class
    public function appendMessage($message, $folder = null, $flags = null, $recent = false)
    {
        if ($this->_quota && $this->checkQuota()) {
            /** * @see Zend_Mail_Storage_Exception */
            throw new Zend_Mail_Storage_Exception('storage is over quota!');
        }

        if ($folder === null) {
            $folder = $this->_currentFolder;
        }

        if (!($folder instanceof Zend_Mail_Storage_Folder)) {