No matter how clever you are, you may encounter such a situation that deleting the important mail in your phone or computer by carelessness. Even if you are careful enough, your email may still not stay safe. Because that your account can be invalided. And your files may be deleted intentionally. Since the emails contain important data, such as attachments sent to your working partners, academic papers, product patent and password confirmation. This situation sounds very bad, isn't it? Everything seems to stay in a mess and can't process further any more.