[Mimedefang] Mailing list breaks DKIM?
mdlist-20140424 at billmail.scconsult.com
Fri May 28 14:02:49 EDT 2021
On 2021-05-28 at 13:14:16 UTC-0400 (Fri, 28 May 2021 10:14:16 -0700)
Kenneth Porter via MIMEDefang <mimedefang at lists.mimedefang.org>
is rumored to have said:
> On 5/28/2021 8:15 AM, Benny Pedersen via MIMEDefang wrote:
>> another maillist that breaks dkim :/
>> would it not be simple to not do this ?
> Does it? My server says the signature on your message is valid.
Yes and yes...
The list server adds the topic tag '[Mimedefang]' to the Subject header
if it is missing it, replaces the From header with its own address in a
"via" form (See the 2nd line of my attribution above), adds a footer,
and may even re-encode the body in some rare cases. All of these break
any normal pre-existing DKIM signature. Except for the From munging, all
of these are common mailing list practices which have been in use since
before the ancestors of DKIM were invented. DKIM is designed to break
with traditional mailing lists. This is not in any way an accident of
The list server ALSO routes its outbound messages through a MTA that
recognizes the list server as a vouched-for entity and which therefore
constructs its own DKIM signature for each message which aligns with the
modified message's From header.
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
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