diff --git a/indexes.json b/indexes.json
index 0d6180c6..cd96687f 100644
--- a/indexes.json
+++ b/indexes.json
@@ -94,7 +94,15 @@
         "name": "by_idate",
         "key": {
             "mailbox": 1,
-            "idate": 1
+            "idate": 1,
+            "_id": 1
+        }
+    }, {
+        "name": "by_idate_newer",
+        "key": {
+            "mailbox": 1,
+            "idate": -1,
+            "_id": -1
         }
     }, {
         "name": "by_idate_newer",