[Mailman-Users] Spam/DKIM issues

Stephen J. Turnbull stephen at xemacs.org
Sun Oct 18 20:08:09 CEST 2015

Marc Bourgeois writes:

 > I'm trying to build a few mailing list with mailman.
 > I've got some trouble with spam/dkim

It's not a Mailman problem as far as I can see.  Mailman doesn't
produce DKIM signatures ever: that's for the MTA to do.

It would help if you explain what the specific symptoms of "trouble"

 > I'm experiencing some difficulties to understand how mailman process
 > outgoing mail with a valid DKIM header.

It does (almost) nothing.  If incoming mail contains a DKIM-Signature
field, it unfolds a multiline header into one line (this is done for
all header fields), and then if REMOVE_DKIM_HEADERS is yes, it removes
the field entirely.  On the way back out it simply folds it again (I
believe this should result in exactly the same header field as
received).  Mailman-generated messages do not have a DKIM signature;
that is the job of the MTA.

 > When a mailing list user send a mail through my list, sometimes
 > header are filled with a X-Google-DKIM-Signature (depend on sender,
 > gmail/google app domain...)

Something other than Mailman (possibly your local MTA or MUA) is doing

 > but no sign of my original DKIM-Signature

What system and mail user agent are you looking at this mail that you
expect to contain a DKIM-Signature field?  What original
DKIM-Signature are you talking about?  Ie, why do you expect there to
be an "original" signature by you?

 > opendkim[1507]: 19D41278A1A5: no signing table match for 'kemkem42 at gmail.com'

I guess that is a DKIM authentication failure.  This is happening in
the MTA (Postfix), not in Mailman.

 > Can someone help me with this ?

The Postfix lists are your best resource.

You may have luck with somebody here knowing about Postfix, too, but
that's not me.  Sorry. :-(


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