Disabling ipv6 (at least in the mail server, in outgoing direction) is
probably the easiest option...
I see on most messages here DKIM-Signature headers apparently from gmail:
"v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;". These
signatures are failing because of the added message footer. No sign of a
DKIM-Signature for lists.bufferbloat.net. You'd need to set that up in the
list MTA.

On Fri, 30 Sep 2016 at 15:42 Dave Täht <dave@taht.net> wrote:

>
>
> On 9/30/16 1:02 AM, Toke Høiland-Jørgensen wrote:
> > Neil Shepperd <nshepperd@gmail.com> writes:
> >
> >> I think I have now accumulated enough spam/nonspam classified emails
> >> to make a statistically signification observation: it seems like all
> >> emails classified as spam from these lists were send from ipv6:
> >>
> >> SPF: PASS with IP 2600:3c03:0:0:f03c:91ff:fe61:86ce
> >>
> >> All emails from bufferbloat.net lists are failing DKIM (because of the
> >> mailing list footer breaking the DKIM signature) which might be worth
> >> fixing, and failing DMARC because all mailing lists fails DMARC
> >> (however google does not have a strict DMARC policy so that shouldn't
> >> matter, I hope).
> >>
> >> By the way, it's not just you, either. I have emails from others on
> >> these lists in my spam folder.
> >>
> >> The distinguishing factor seems to be whether the email was sent from
> >> the lists.bufferbloat.net ipv6 address. Unless this address
> >> corresponds to some kind of tunnel broker possibly also used by
> >> spammers, I can only assume this is some kind of bug (after all, it
> >> was spf validated so the address shouldn't matter at that point?).
> >
> > Indeed, gmail requires extra measures for IPv6:
> > https://support.google.com/mail/answer/81126 (scroll down to "Additional
> > guidelines for IPv6").
> >
> > Fixing DKIM might be worthwhile :)
>
> But it passes the spf check?? And the reverse lookup is correct.
>
> How about I just disable ipv6?
>
> Have no idea why dkim doesn't work.
>
> >
> > -Toke
> > _______________________________________________
> > Cake mailing list
> > Cake@lists.bufferbloat.net
> > https://lists.bufferbloat.net/listinfo/cake
> >
> _______________________________________________
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> Cake@lists.bufferbloat.net
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>