The main threat of an email
StealthMail uses email to send crypto-links that do not contain any user information. Only through crypto-links can an authorized user access encrypted email content and attachments right in the user’s own email client, keeping the information safe from would be cybercriminals.
Thus, third-party email servers will only receive and transfer crypto-links, which can't be decrypted as they do not contain any user data. This approach to protecting users' emails makes SMTP, SSL/TLS vulnerabilities complete non-issues.