The startup scripts will not run if any users are added to the opendkim group for security reasons, but it uses those groups to create the local socket, so if you use mail services like postfix which run as their own users there's no way without modifying the scripts or modifying permissions after every restart to grant postfix the ability to use it. minor annoyance as it's just something I have to fix after every update but you'd think it's such a common pairing...