List change - munging for From addresses

[Konstantin Ryabitsev]

On Fri, Aug 02, 2024 at 01:03:47PM GMT, Stephen Rothwell wrote:
> As more and more sites are using DKIM signing or emails (and DMARC),
> more and more of the list traffic is not being delivered due to Mailman
> altering messages in subtle ways (so the DKIM signature is no longer
> valid).  The easiest thing to do is to tell Mailman to munge the From:
> address so that the messages come from the mailing list itself.  It
> also adds a Reply-To: header with the original sender's address.
> 
> So a message from me to the list will now have
> 
> From: Stephen Rothwell via Linuxppc-dev <linuxppc-dev at lists.ozlabs.org>
> Reply-To: Stephen Rothwell <sfr at canb.auug.org.au>
> 
> The only real downside to this (I think) is that if you take a message
> from the list containing a patch and apply that to a git tree you will
> have to fix up the Author appropriately.
> 
> Konstantin, I assume (hope?) that b4 may have some way of fixing the
> authorship up?

Not really, for two reasons:

- X-Original-From is widely used, but isn't really a standard header.
- From-munging breaks end-to-end attestation, so we consider x-original-from
  and similar headers a potential impersonation attempt and ignore them.

I would generally say that From-munging isn't a great option for any list that
receives patches. A much better approach is to just not modify the message
headers or message body. This should be possible with mailman.

-K