The main threat of an Email
StealthMail uses Email to send only crypto-links that do not contain any user information whatsoever. Only through crypto-links can an authorized user access encrypted Email content and attachments.
Thus, untrusted 3rd party mail servers will only receive and transfer crypto-links, which can't be decrypted as they do not contain data. This approach to protecting Emails makes SMTP, SSL/TLS vulnerabilities complete non-issues.