diff -ru qpsmtpd-0.40/plugins/require_resolvable_fromhost qpsmtpd-0.40.fix/plugins/require_resolvable_fromhost
--- qpsmtpd-0.40/plugins/require_resolvable_fromhost	2007-06-14 13:57:24.000000000 -0400
+++ qpsmtpd-0.40.fix/plugins/require_resolvable_fromhost	2008-08-11 16:26:59.000000000 -0400
@@ -53,7 +53,12 @@
   $res->udp_timeout(30);
   my @mx = mx($res, $host);
   foreach my $mx (@mx) {
-    return mx_valid($self, $mx->exchange, $host);
+    # if any MX is valid, then we consider the domain
+    # resolvable
+    return 1 if mx_valid($self, $mx->exchange, $host);
+    # if there are MX records, and we got here,
+    # then none of them are valid
+    return 0 if (@mx > 0);
   }
   my $query = $res->search($host);
   if ($query) {