Hi, We don’t have an option for it within the plugin. It’s not something we advertise. The simple shipping option available in the plugin is documented here:
You could perhaps put a message on your site that explains which countries you do support? You can maybe create a page listing the supported countries where you ship and the shipping rules. Then you can link to that page from your message. Also, you can add that to your terms and conditions.
I will also add this on our feature wish list document to consider a feature for it in the future.