lib/PublicInbox/LeiMailSync.pm | 1 +

diff --git a/lib/PublicInbox/LeiMailSync.pm b/lib/PublicInbox/LeiMailSync.pm
index 57b56b3cbd6282c22f3ba1fff89968dbc5c1b7df..bf8fb7de1771ebce60dddbccd9288a8751f43985 100644
--- a/lib/PublicInbox/LeiMailSync.pm
+++ b/lib/PublicInbox/LeiMailSync.pm
@@ -330,6 +330,7 @@ --all= not compatible with @$folders on command-line
 EOM
 	my %x = map { $_ => $_ } split(/,/, $all);
 	my @ok = grep(defined, delete(@x{qw(local remote), ''}));
+	push(@ok, '') if $all eq '';
 	my @no = keys %x;
 	if (@no) {
 		@no = (join(',', @no));