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Comment by baudehlo | Hacker News Reader

SMTP with TLS doesn't leak any metadata except the connecting IP address. And with DMARC you can mandate it.

Calls for whole new protocols for email are usually made by people who don't understand the email ecosystem as it currently stands.

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But SMTP with TLS is opportunistic -- and if we're talking "national state secrets" it's trivial for a state to MITM the connection and do a TLS downgrade attack.

Not if the receiving smtp server implements DMARC

Is DMARC like HSTS for SMTP?

DMARC doesn't have a STARTTLS policy. I think you mean DANE / TLSA.

In which case you're conceding security to governments anyways.

Sorry Tony, you're absolutely right. Got my acronyms wrong. Thank you :)

(The parent is Tony Finch, a very smart email guy who runs email for the university of Cambridge)

Can the TLS be enforced by the sender all the way through the chain to the destination mailbox?

Yes, as well as PGP or S/MIME. It just depends or your relay configuration. We've implemented it switch able. We've customers that are bouncing non PGP encrypted E-Mails.

The sender (the sender's service provider or organization) decides when to use TLS while the message bounces around internally, then (this is the typical long hop) the recipient's server and the sender's SMTP client negotiate, and then the recipient gets to decide.

The sender may have opinions, but as soon as the message is handed over to the recipient's server, that's it. That's the end of the sender's influence, and that's how it has to be on a global internet. People can connect without having their infrastructure approved by anyone else.

No, it can't. The receiver could be using a non secure SMTP server.

If you actually care about the data, it does nothing. It only guarantees that the front door is encrypted.

With the number of cloud anti spam and archive companies out there, you have no idea what happens between those providers and the mail servers.

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