public function isMaintenanceMode($ipAddress = null) {
		if ($ipAddress) {
			$this->enableDebugModeForWhitelist($ipAddress);
		}

		if (!file_exists($this->file)) {
			return false;
		}

		$content = file_get_contents($this->file);
		if ($content === false) {
			return false;
		}

		if ($content > 0 && $content < time()) {
			$this->setMaintenanceMode(false);
			return false;
		}

		if ($ipAddress) {
			$file = TMP . 'maintenanceOverride-' . $this->_slugIp($ipAddress) . '.txt';
			if (file_exists($file)) {
				Configure::write('Maintenance.overwrite', $ipAddress);
				return false;
			}
		}
		return true;
	}