lib/PublicInbox/WatchMaildir.pm | 17 +++++++----------
 t/watch_maildir.t               | 15 +++++++++++++++

diff --git a/lib/PublicInbox/WatchMaildir.pm b/lib/PublicInbox/WatchMaildir.pm
index 496199c90f57a2d955d98fd07c0abc2a8659ab25..c1f3c5c258f170d59b7562db7de1aa03a7fa28bf 100644
--- a/lib/PublicInbox/WatchMaildir.pm
+++ b/lib/PublicInbox/WatchMaildir.pm
@@ -52,15 +52,6 @@ 		for my $dir (@$dirs) {
 			if (is_maildir($dir)) {
 				# skip "new", no MUA has seen it, yet.
 				my $cur = "$dir/cur";
-				my $old = $mdmap{$cur};
-				if (ref($old)) {
-					foreach my $ibx (@$old) {
-						warn <<"";
-"$cur already watched for `$ibx->{name}'
-
-					}
-					die;
-				}
 				push @mdir, $cur;
 				$uniq{$cur}++;
 				$mdmap{$cur} = 'watchspam';
@@ -84,9 +75,15 @@ 		if (is_maildir($watch)) {
 			compile_watchheaders($ibx);
 			my $new = "$watch/new";
 			my $cur = "$watch/cur";
+			my $ws = $mdmap{$cur};
+			if ($ws && !ref($ws) && $ws eq 'watchspam') {
+				warn <<EOF;
+E: $cur is a spam folder and cannot be used for `$ibx->{name}' input
+EOF
+				return; # onto next inbox
+			}
 			push @mdir, $new unless $uniq{$new}++;
 			push @mdir, $cur unless $uniq{$cur}++;
-
 			push @{$mdmap{$new} ||= []}, $ibx;
 			push @{$mdmap{$cur} ||= []}, $ibx;
 		} else {
diff --git a/t/watch_maildir.t b/t/watch_maildir.t
index 66955072cd58dc412eeeb5936493207429b2c870..33a3458bd4dca7a63dbfc5aa791093f1416f8919 100644
--- a/t/watch_maildir.t
+++ b/t/watch_maildir.t
@@ -32,6 +32,21 @@ ok(POSIX::mkfifo("$maildir/cur/fifo", 0777),
 	'create FIFO to ensure we do not get stuck on it :P');
 my $sem = PublicInbox::Emergency->new($spamdir); # create dirs
 
+{
+	my @w;
+	local $SIG{__WARN__} = sub { push @w, @_ };
+	my $config = PublicInbox::Config->new(\<<EOF);
+$cfgpfx.address=$addr
+$cfgpfx.inboxdir=$git_dir
+$cfgpfx.watch=maildir:$spamdir
+publicinboxlearn.watchspam=maildir:$spamdir
+EOF
+	my $wm = PublicInbox::WatchMaildir->new($config);
+	is(scalar grep(/is a spam folder/, @w), 1, 'got warning about spam');
+	is_deeply($wm->{mdmap}, { "$spamdir/cur" => 'watchspam' },
+		'only got the spam folder to watch');
+}
+
 my $config = PublicInbox::Config->new(\<<EOF);
 $cfgpfx.address=$addr
 $cfgpfx.inboxdir=$git_dir