+The L<rfc2919|https://tools.ietf.org/html/rfc2919> header without
+angle brackets for L<public-inbox-mda(1)> deliveries and
+L<public-inbox-watch(1)>.
+
+For public-inbox-watch users, this is a shortcut for specifying
+C<publicinbox.$NAME.watchheader=List-Id:E<lt>foo.example.comE<gt>>
+
+For public-inbox-mda users, this may be used to avoid recipient
+matching via C<ORIGINAL_RECIPIENT> environment variable.
+
+This may be specified multiple times for merging multiple mailing
+lists into a single public-inbox, only one C<List-Id> header
+needs to match.
+
+Default: none