Re: [mlmmj] Problem with mail sent by @orange.fr to @protonmail.com

On Mon, Nov 27, 2023 at 10:55:22PM +0100, Baptiste Daroussin wrote:
> Well if you don t alter the email (no subject modifications for example)

So, can we stop the mlmmj list from doing this? :)

> I first went down the "munging from" path using rspamd in front of mlmmj
> (hence the new feature of suporting X_ORIGINAL_FROM in mlmmj 1.4.0). But
> then realised that if I stop altering the emails (just play with custom
> headers) then the dkim signatures remains valid and all mail providers do
> accept the emails as only being relayed.

This should continue to work for a while, but soon we'll need to work on being
conformant with DARA [1], which will require adding Forwarded-To: headers and
ARC-signing every outgoing message. Yes, this means that if your mailing list
has 5,000 subscribers, you'll need to cryptographically sign 5,000 individual
messages.

We probably have a couple of years before that starts being relevant, though.

-K

[1] https://datatracker.ietf.org/doc/draft-chuang-replay-resistant-arc/