[ClusterLabs] @ maillist Admins - DMARC (yahoo)

[kgaillot at redhat.com]

On Tue, 2021-07-13 at 14:46 +0300, Andrei Borzenkov wrote:
> On Mon, Jul 12, 2021 at 5:50 PM <kgaillot at redhat.com> wrote:
> > 
> > On Sat, 2021-07-10 at 12:34 +0100, lejeczek wrote:
> > > Hi Admins(of this mailing list)
> > > 
> > > Could you please fix in DMARC(s) so those of us who are on
> > > Yahoo would be able to receive own emails/thread.
> > > 
> > > many thanks, L.
> > 
> > I suppose we should do something, since this is likely to be more
> > of an
> > issue as time goes on. Unfortunately, it's not as simple as
> > flipping a
> > switch. These are the two reasonable choices:
> > 
> 
> The problem is, both are incomplete.

Unfortunately that's correct, there is no way to make everybody happy.


> > (1) Change the "From" on list messages so that they appear to be
> > from
> > the list, rather than the poster. For example, your posts would
> > show up
> > as "From: lejeczek via ClusterLabs Users <users at clusterlabs.org>"
> > rather than "From: lejeczek <peljasz at yahoo.co.uk>". This is less
> > intrusive but makes it more difficult to reply directly to the
> > sender,
> > add the sender to an address book, etc.
> > 
> 
> This will pass SPF but fail DKIM
> 
> > 
> > (2) Stop adding [ClusterLabs] to subject lines, setting ReplyTo: to
> > the
> > list instead of original author, and adding the list signature.
> > This is
> > more standards-compliant, since the List-* headers can still be
> > used
> > for filtering, unsubscribing, and replying to the list, but not all
> > mail clients make those easy to use.
> > 
> 
> This will pass DKIM but fail SPF.
> 
> I do not know how many domains implement only SPF, only DKIM or both.

Yes, that is a well-known issue, and for that reason I think it's very
rare for DMARC to be used with only one of them, even though the DMARC
standard allows that.

(A domain that doesn't use DMARC can use just one of SPF or DKIM
without problems -- in fact, clusterlabs.org uses SPF but not DKIM or
DMARC.)

> > 
> > Anyone have preferences for one over the other?
> > 
> > (Less reasonable options include wrapping every post in MIME, and
> > disallowing users from DMARC domains to post to the list.)
> 
> Well, enabling ARC in addition to either of the options may somehow
> mitigate them. It depends on *recipient* domain support though. Also
> I
> am not sure whether Mailman 2.x supports it.
> 
> From a personal perspective, I already filter by list ids and
> [ClusterLabs] just wastes screen real estate. But I remember somewhat
> heated responses when openSUSE changed list software and dropped
> prefixes - apparently quite some users were using single mailbox and
> relied on prefixes to prioritize message reading.

Yes, I worry about that. But I'm afraid the technology has evolved to a
point where that's no longer a reasonable approach to email.

I am leaning to (2) for that reason; it seems to be the more standards-
compliant and future-oriented approach. I know the new format would
take some getting used to, but hopefully it smooths out over time.
-- 
Ken Gaillot <kgaillot at redhat.com>