Hello, The correct solution is:
Change /lib/systemd/system/opendkim.serviceline 11 to: ExecStart=/usr/sbin/opendkim -x /etc/opendkim.confThis changeneeds to be implemented with a small incremental update to the currect stretch version, since it is essentially a breakage bug (affects functionality). The only thing that needs to be changed is to let opendkim read its own configuration file, there are no other changes needed anywhere else in the package.
Thank you