[Mailman-Users] DMARC-related bounces due to AOL sender; from_is_list or anonymous_list?

Mark Sapiro mark at msapiro.net
Wed Nov 23 13:37:36 EST 2016

On 11/23/2016 08:53 AM, Matt Morgan wrote:
> I understand that my choices for fixing this are either from_is_list or
> anonymous_list, and since this is an old server (2.1.12) that I recently
> took over (I have to stop using that excuse soon, I know), I can't do
> from_is_list.

Actually, in 2.1.18+ dmarc_moderation_action is more often than not
preferable to from_is_list.

See <https://wiki.list.org/x/17891458> for other possible mitigations
some of which apply to older Mailman versions.

> I need to update desperately. In other recent discussions, though, I seen
> that Microsoft in particular is starting to make trouble even with
> from_is_list, i.e., when the sender and reply-to don't match, with the
> expectation being that one day their warnings will become rejections.

Actually, the current Microsoft warning is issued when the From: and To:
(or Cc:) addresses are the same. This affects anonymous_list as well as
DMARC mitigations.

It seems the (partial) way around all of this is to apply DMARC
mitigations when necessary or always (via dmarc_moderation_action or
from_is_list) and to set personalize to Full personalization so that To:
is the recipient, not the list.

Without better knowledge of Microsoft's rule, it's difficult to know how
to deal with it, and I'm sure Microsoft would consider such information
to be proprietary.

> In that light, should I just be moving to anonymous_list anyway? Training
> users to identify themselves in the body of their messages seems like the
> potential big issue there. Anything else?

As noted above, anonymous_list is not a solution in general. You might
consider anonymous_list as a DMARC mitigation in pre-2.1.16 only, but
better to upgrade.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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