mailman From rewriting [was perf jit: genelf makes assumptions about endian]

[Michael Ellerman]

On Wed, 2016-03-30 at 13:30 +0800, Jeremy Kerr wrote:
> > > Do you know why mailman would be re-writing From: there? It's confusing
> > > patchwork, as multiple mails are now coming from that address.
> >
> > Yep, Anton posts from samba.org.  They publish a DMARC policy that
> > breaks mailing lists.
>
> (╯°□°)╯︵ ┻━━┻
>
> This also breaks git-am:
>
>   [jk at pudge linux]$ git am incoming.eml
>   Applying: perf jit: genelf makes assumptions about endian
>   [jk at pudge linux]$ git log --format='format:%an <%ae>' -1
>   Anton Blanchard via Linuxppc-dev <linuxppc-dev at lists.ozlabs.org>

Indeed.

Personally I only apply patches from patchwork, so if it could get the sender
right (which I think it needs to anyway), then I'd be OK.

> > The best thing we can do is to do the above rewrite of the From header.
>
> OK, it looks like we're stuck either way with DMARC. Could we make this
> a little more tolerable by stashing the original From: value in a new
> header? I know it's already in Reply-To, but that could also be set by
> arbitrary other (non-mailman-DMARC-rewrite) sources.

That'd be nice, or even just an X-did-DMARC-Rewrite: True.

> Alternatively, if there's some other way to tell that this a mail has
> been rewritten, we can know to use Reply-To in preference to From.

I think checking for mails from the list address should work in practice. And
it has the advantage that it works with the existing versions of mailman. If we
need a new mechanism then we have to wait to get patched mailman in the wild.

> Otherwise, I guess we could require that *all patch submitters* put
> their From: line in the content of their mails, as git send-email does
> when user != author. But that's a little less-than-optimal.

I had a quick look at git-send-email/git-format-patch and there doesn't seem to
be any way to force a From line. So I think that's a medium term issue that the
git folks will have to look at fixing. Maybe they've already noticed, I'm not
on the git list.

cheers