+=item B<-l> I<filename> (check against list)
+
+Check each group against a list of valid newsgroups read from
+I<filename>, one group on each line and ignoring everything after the
+first whitespace (so you can use a file in checkgroups format or (part
+of) your INN active file).
+
+Newsgroups not found in I<filename> will be dropped (and logged to
+STDERR), and newsgroups found in I<filename> but having no postings
+will be added with a count of 0 (and logged to STDERR).
+