public function discovery($params) {
		if (is_string($params)) {
			$params = array('email' => $params);
		}
		else {
			$params = $this->_filterParams($params, array('email'), array('email'));
			if ($params === false) {
				throw new InvalidArgumentException("params array contains invalid parameters or misses required parameters");
			}
		}
		return $this->get(null, 'discovery?source_type=imap&email=' . rawurlencode($params['email']));
	}