Default: none.
+=item -c KEY=VALUE
+
+Allow setting arbitrary configs as C<publicinbox.$NAME.$KEY>.
+This is idempotent for the same C<VALUE>, but allows setting
+multiple values for keys such as C<publicinbox.$NAME.url> and
+C<publicinbox.$NAME.watch>.
+
=item --skip-artnum
This option allows archivists to publish incomplete archives