[Mailman-Users] Which from, reply and DMARC settings for a discussion group?

Mark Sapiro mark at msapiro.net
Mon Jan 19 01:28:54 CET 2015

On 01/18/2015 03:14 PM, Clare Redstone wrote:
> I've been trying to understand from_is_list, anonymous_list,
> first_strip_reply_to, reply_goes_to_list and reply_to_address and don't know
> if I need to change options here or dmarc_moderation_action or both.

It's very tricky, and 2.1.19 will get you closer to what you want than
2.1.18-1 will, but 2.1.19 isn't released yet.

> What I'm hoping to achieve:
> 1.       That when people hit the "reply" button, the reply goes to the
> list.
> (Currently most of the time it fills in both the poster's and the list's
> address. I just tried a test from gmail using Outlook and it only filled in
> the poster's address.)

Set the following
first_strip_reply_to = Yes
reply_goes_to_list = This list
reply_to_address - doesn't matter as it is only used if
reply_goes_to_list  is Explicit address.

Also set from_is_list to No and dmarc_moderation_action to either Munge
from or Wrap message. Actually, I think Wrap message is the better
transformation, but I had to back off from that on my lists because of
complaints (mostly from users of iThings) that the messages were
difficult to deal with in various ways.

This will still put the poster's address in Reply-To: along with the
list address. This is the change for 2.1.19 which will put the poster's
address in Cc: in this case.

> 2.       It would be good if the poster's email address was visible, so that
> someone could chose to reply privately. In the same way as it used to be.
> But I want that to be a deliberate choice. I think that since DMARC altered
> how Mailman functioned, some are replying accidentally only to the poster
> (as in the gmail example above) and don't realise that's happened. So we
> lose out on the group discussion.

Gmail itself will do the right thing; at least it does in a test I just
did, but what Outlook does with a list post originally from gmail (if
that's what you tested) is an Outlook issue.

In any case, as I note elsewhere, set from_is_list to No and control
From: munging with dmarc_moderation_action and posts from gmail won't be

> This isn't essential. In fact in some ways it may be a good thing if
> posters' email addresses aren't visible. It's a self-help group and some
> people prefer to remain anonymous. Occasionally people hadn't realised their
> email addresses became visible to the group when they posted.

If you don't want the poster's address to be visible, you can set
anonymous_list = Yes, and that will remove all headers that could be
used to identify the poster or the poster's domain. If you do that, you
can set from_is_list to No (because anonymous list does this anyway) and
dmarc_moderation_action to Accept.

> 3.       None (or as few as possible) messages not reaching intended
> recipients due to providers' and email clients' settings, DMARC etc causing
> problems. None (or as few as possible) members being suspended due to
> excessive bounces and the list being blacklisted.

You need to apply some kind of DMARC mitigation to accomplish this.
Setting anonymous_list = Yes counts as a DMARC mitigation in this case.

> 4.       If there's a choice between 1 and 2 (ie, I can't have both) then 1
> takes priority. There's been a noticeable drop in group discussion so I
> wonder whether replies have been going to individuals quite often, instead
> of the group. If someone needs to reply to someone privately, I think it's
> still possible. If push comes to shove, they just post a reply saying "you
> can email me off-list at XX at yy." That's no different from the senders' email
> addresses being visible before in any case.

You can't have 1 with MM 2.1.18-1. What you get with the settings I
suggest is that both the list address and the poster's address are in
Reply-To:.  In this case, a 'reply' is supposed to go to both the list
and the poster, but evidently, there are some MUAs (mail clients) that
are non-conformant in this respect.

Note however that for a non-anonymous list, setting from_is_list to No
and using dmarc_moderation_action to control From: munging is preferable
because then only messages From: AOL and Yahoo addresses (at present)
will be munged.

> Is this possible? I'd be grateful if someone would tell me what settings I
> need for this. Sorry I haven't been able to understand it myself.

You may find the bug at
<https://bugs.launchpad.net/mailman/+bug/1407098> of interest.

Also, these comments from the code express my thinking on this.

# MAS: We need to do some things with the original From: if we've munged
# it for DMARC mitigation.  We have goals for this process which are
# not completely compatible, so we do the best we can.  Our goals are:
# 1) as long as the list is not anonymous, the original From: address
#    should be obviously exposed, i.e. not just in a header that MUAs
#    don't display.
# 2) the original From: address should not be in a comment or display
#    name in the new From: because it is claimed that multiple domains
#    in any fields in From: are indicative of spamminess.  This means
#    it should be in Reply-To: or Cc:.
# 3) the behavior of an MUA doing a 'reply' or 'reply all' should be
#    consistent regardless of whether or not the From: is munged.
# Goal 3) implies sometimes the original From: should be in Reply-To:
# and sometimes in Cc:, and even so, this goal won't be achieved in
# all cases with all MUAs.  In cases of conflict, the above ordering of
# goals is priority order.

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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