+ TnyMsg *msg;
+ GSList *recipients, *node;
+ gboolean has_recipients_to_add;
+
+ g_return_val_if_fail (MODEST_IS_DIMMING_RULE (user_data), FALSE);
+ g_return_val_if_fail (MODEST_IS_MSG_VIEW_WINDOW (win), FALSE);
+
+ msg = modest_msg_view_window_get_message (MODEST_MSG_VIEW_WINDOW (win));
+ recipients = modest_tny_msg_get_all_recipients_list (msg);
+
+ has_recipients_to_add = FALSE;
+ for (node = recipients; node != NULL; node = g_slist_next (node)) {
+ if (!modest_address_book_has_address ((const gchar *) node->data)) {
+ has_recipients_to_add = TRUE;
+ break;
+ }
+ }
+
+ g_slist_foreach (recipients, (GFunc) g_free, NULL);
+ g_slist_free (recipients);
+ g_object_unref (msg);
+
+ return !has_recipients_to_add;