+ $res = $cb->(GET('/test/no-subject-at-all@example.com/raw'));
+ like($res->header('Content-Disposition'),
+ qr/filename=no-subject\.txt/);
+ $res = $cb->(GET('/test/no-subject-at-all@example.com/t.mbox.gz'));
+ like($res->header('Content-Disposition'),
+ qr/filename=no-subject\.mbox\.gz/);