The suggestion in the comment by SebastianNielsen is exactly what is done by the from_is_list Wrap Message setting first implemented in Mailman 2.1.16 and made more generally available (not requiring site option to enable) in Mailman 2.1.18. See DEV/DMARC.
A short link to this page is
https://wiki.list.org/x/17892021
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