diff --git a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/EmailQueueItem.json b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/EmailQueueItem.json
index d66dd5d32d..8d79930fb7 100644
--- a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/EmailQueueItem.json
+++ b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/EmailQueueItem.json
@@ -24,7 +24,8 @@
         },
         "sentAt": {
             "type": "datetime",
-            "readOnly": true
+            "readOnly": true,
+            "index": true
         },
         "emailAddress": {
             "type": "varchar",
@@ -49,4 +50,4 @@
         "orderBy": "createdAt",
         "order": "desc"
     }
-}
\ No newline at end of file
+}