Patchwork and DMARC emails.

[Etan Kissling]

On 18.02.21, 05:15, "openwrt-devel on behalf of Sam Kuper" <openwrt-devel-bounces at lists.openwrt.org on behalf of sampablokuper at posteo.net> wrote:

> On Wed, Feb 17, 2021 at 02:47:57PM +0100, Etan Kissling wrote:
> > On 08.02.21, 10:33, Rosen Penev wrote:
> >>> My patches don't end up in Patchwork for some reason.
> >> It's because of DMARC. [..]
> >
> > Thanks for the hint about DMARC leading to Patchwork issues. [..]
> >
> > It seems that the OpenWrt mailing list breaks the signature by adding
> > the 'openwrt-devel mailing list' footer.
>
> IIUC, the OpenWrt mailing list software (Mailman 2.1.29, last time I
> checked) does not "break the signature".
>
> Instead, it wraps the original message and modifies the "From:" header
> before distributing the mail to list subscribers.  That wrapped message
> is then (either by Mailman or by the MTA, I'm not sure) provided with a
> new signature that is valid for the domain in the new "From:" header.

Thanks for looking into this!

You are right, sorry for not being clear enough. The wrapping is the
workaround to avoid breaking the signature. However, it is also possible
to just forward DKIM messages as is (no changes to From, Subject, Body).
In that case, the footer would have to be removed. This only works with
DKIM present, it doesn't when DMARC and SPF are used but no DKIM. Not
sure how popular that problematic combination is, though.

This blog post adds some more background as well:
https://begriffs.com/posts/2018-09-18-dmarc-mailing-list.html

Either variant should work:

- Wrapping of the message (openwrt-devel behaviour)
- Mangling 'From' header (dnsmasq-discuss behaviour)
- Keep From / Subject / Body as-is (netfilter-devel behaviour)

On openwrt-devel the empty subject, loss of thread hierarchy in the web
archive as well as Patchwork problems seem to arise. Hoping that the fix
for empty subjects will make Patchwork problems go away.

On dnsmasq-discuss _sometimes_ the message still ends up in junk,
especially when it goes through moderation queue (e.g., long message).
I don't think they use Patchwork, so not sure how Patchwork likes the
mangled from headers and subject line prefix that they add.

On netfilter-devel, I never had any problems regarding junk filtering
or Patchwork. Linux kernel mailing lists can feel a bit slow sometimes
but it does not seem to be related to email authentication.
 Authentication-results: apple.com;	spf=pass
 smtp.mailfrom=netfilter-devel-owner at vger.kernel.org;	dkim=pass
 header.s=20180706 header.d=apple.com

Cheers

Etan