Hello,
the DMARC Mitigation action “Replace From: with list address” is
evaluated in mailman/handlers/dmarc.py:munged_headers(). In the case,
where From: is a non-member email address, without display part, which
non-member may post, this happens:
realname = email
realname = re.sub(r'@([^ .]+\.)+[^ .]+$', '---', realname)
with _.using(mlist.preferred_language.code):
via = _('${realname} via ${mlist.display_name}')
display_name = str(Header(via, mlist.preferred_language.charset))
value = [('From', formataddr((display_name, mlist.posting_address)))]
In short, if a@b is a non-member, who may post to mailing list “E
<c@d>”, and b is DMARC-protected, the final distrubuted email will have
From: "a--- via E <c@d>"
Reply-To: a@b
compare to the IETF mailing lists, which would send:
From: <a=40b@d> where a and b are from a@b, d is from c@d
The bottom of https://answers.uillinois.edu/illinois/page.php?id=86787
describes the mitigariton options offered by Sympa:
display name
From: User Name <listn...@lists.illinois.edu>
display name and e-mail
From: “User Name” (userem...@address.com) <
listn...@lists.illinois.edu >
email “via Mailing List”
From: “User Name” (userem...@address.com via listName Mailing List)
<listn...@lists.illinois.edu>
name “via Mailing List”
From: “User Name” <listn...@lists.illinois.edu>
(the website likely means:)
From: “User Name via listName” <listn...@lists.illinois.edu>
As can be seen, the other MLMs do not replace domains with --- . I
find ugly the --- , inserted by mailman. In my real-world case the
From: is a...@example.org, the ML name is a...@l.example.org (localname
is the same, the domains are different). The result is:
From: aaa--- via Aaa <a...@l.example.org>
So there is twice trippe-A and @example.org disappeared. Mentioning
twice AAA in the display name in this case really has to added value.
That said, I propose removing now the line
realname = re.sub(r'@([^ .]+\.)+[^ .]+$', '---', realname)
and in the future offer as options:
From: User Name <listn...@lists.illinois.edu>
From: “User Name” (userem...@address.com) <
listn...@lists.illinois.edu >
From: “User Name” (userem...@address.com via listName Mailing List)
<listn...@lists.illinois.edu>
From: “User Name via listName” <listn...@lists.illinois.edu>
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