Forcing TLS for the MTA at each end is about network encryption (i.e. akin to HTTPS) this &quot;solution&quot; is about encrypting the contents of the message envelope, i.e. restricting who can read the contents of the message regardless of how its transferred.<p>As I mentioned elsewhere, it is however yet another non-solution, for the same reason you queried - it&#x27;s all reliant on a single provider.<p>Real end-to-end encrypted email is when your mail client uses either S&#x2F;MIME or PGP&#x2F;GPG to encrypt your message using the recipient&#x27;s public key(s). In that situation, it doesn&#x27;t matter what mail service they use, or what network transport the MTA&#x27;s use - it&#x27;s readable only by them (well technically only by anyone with the appropriate private key - I&#x27;m going to assume people are protecting their keys).