try setting mail.log permissions during setup

setup/system.sh

@@ -407,4 +407,5 @@ EOF
 # Before miabldap v56, nsd.log was owned by nsd:nsd, which would
 # prevent rsyslog from writing to it. Fix the ownership.
 [ -e /var/log/nsd.log ] && chown syslog:adm /var/log/nsd.log
+[ -e /var/log/mail.log ] && chown syslog:adm /var/log/mail.log
 restart_service rsyslog