--- simplenews_template_org.module	2010-06-30 22:44:51.000000000 +1000
+++ simplenews_template.module	2010-09-13 10:37:36.000000000 +1000
@@ -62,7 +62,8 @@ function simplenews_template_menu() {
  */
 function _simplenews_template_preview_access($nid) {
   $node = node_load($nid);
-  return $node && $node->type == 'simplenews' && user_access('access newsletter preview');
+  $simplenews_content_types = variable_get('simplenews_content_types', array('simplenews' => 'simplenews'));
+  return $node && in_array($node->type, $simplenews_content_types) && user_access('access newsletter preview');
 }
 
 /**