[Mailman-Developers] Mailman introducing spurious References: or In-Reply-To: headers?

hi mailman folks--

over on dns-privacy@ietf.org, one of the participants (Hosnieh Rafiee, cc'ed here) suggests that mailman appears to be introducing spurious References: and In-Reply-To: headers (see the attached message below for some of the discussion.

Can you confirm whether this is a function of mailman (e.g. to try to merge threads between people whose MUAs don't properly set In-Reply-To: or References:? If so, is there anything we can do to avoid it happening in the future?

I believe the ietf.org mailman installation is running 2.1.15, fwiw.

Regards,

    --dkg