Out of the box, the DKIM signature feature of UTM (here: 9.718-5) covers sevral common headers, including several headers related to list subscription management, in particular List-Unsubscribe: and a few more. However, it does not cover List-Unsubscribe-Post:, which is unfortunate because having that header covered by the DKIM signature is somewhat of a must nowadays (cf. https://datatracker.ietf.org/doc/html/rfc8058#section-3.1).
Is there anything I can tweak manually to fix this?