As per RFC 8058 and newest policies by Google and other big players, it is practically mandatory to have DKIM signatures that cover also the List-Unsubscribe-Post: header.
Unfortunately, my UTM 9.718-5 does not do so, though it does cover List-Unsubscribe: and several more headers out of the box.
Is there any way I can tweak it to also cover the List-Unsubscribe-Post: header in its DKIM signatures?