[Mailman-Users] Ignore DMARC bounces?

Sparr sparr0 at gmail.com
Fri Jun 13 16:24:07 CEST 2014

On 05/02/2014 10:51 PM, Mark Sapiro wrote:
> On 05/02/2014 05:21 PM, Andrew Partan wrote:
> > Is there some way of ignoring the DMCAC bounces?  That way a message
> > From: some... at yahoo.com will not not increase the bounce count of
> > all Yahoo, AOL, Hotmail, ATT, MSN, and Comcast users.
> It's difficult. If The local MTA is refused and reports directly to
> Mailman at SMTP time, Mailman will only see the SMTP status, e.g. 554,
> 521, or 550 in your examples. It is not possible to distinguish DMARC
> from other failures just by this 5xx status.
> More likely, the local MTA accepted the message from Mailman and is now
> delivering a DSN. If every MTA delivered an RFC 3464 compliant DSN with
> an RFC 1893 extended status code, one could just ignore 5.7.x bounces,
> but even your example services don't all use a 5.7.x code even though
> the RFC is clear that that is the code for security or policy rejection.
> Then there is the fact that many real world MTAs report in their own way
> and don't necessarily provide enough information to tell what the reason
> is. Take a look at Mailman/Bouncers/* to get an idea of what you'd be up
> against.
> > Yahoo & ATT say this:
> >       554 5.7.9 Message not accepted for policy reasons.  See
> >       http://postmaster.yahoo.com/errors/postmaster-28.html
> >
> > AOL says this:
> >       521 5.2.1 :  (DMARC) This message failed DMARC Evaluation
> >       and is being refused due to provided DMARC Policy
> >
> > Comcast says this:
> >       550 5.2.0 x4fx1n03n5DGQ1A034fysP Message rejected due to
> >       DMARC. Please see
> >       http://postmaster.comcast.net/smtp-error-codes.php#DM000001
> >
> > MSN/Hotmail say this:
> >       550 5.7.0 (BAY0-MCn-Fn) Unfortunately, messages from (N.N.N.N)
> >       on behalf of (yahoo.com) could not be delivered due to
> >       domain owner policy restrictions.)

Yahoo, ATT, MSN, Hotmail, and Google all seem to respond with 5.7.x
status codes. If ignoring 5.7.x responses is a good approach, and a
large fraction (significant majority, I suspect) of users use services
that give 5.7.x responses, and mailman is already able to parse those
responses, then it sounds like ignoring 5.7.x bounces (or counting
them differently) is a viable step to take.

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