diff --git a/lib/storage.js b/lib/storage.js
index ac4bcb4..cc0bcaf 100644
--- a/lib/storage.js
+++ b/lib/storage.js
@@ -64,6 +64,9 @@ Storage.prototype._createIndexes = function() {
   this.db.collection(collections.ADDRESSES).createIndex({
     address: 1,
   });
+  this.db.collection(collections.EMAIL_QUEUE).createIndex({
+    id: 1,
+  });
   this.db.collection(collections.EMAIL_QUEUE).createIndex({
     notificationId: 1,
   });
@@ -628,7 +631,7 @@ Storage.prototype.storeActiveAddresses = function(walletId, addresses, cb) {
 };
 
 // --------         ---------------------------  Total
-//           > Time >                  
+//           > Time >
 //                       ^to     <=  ^from
 //                       ^fwdIndex  =>  ^end
 Storage.prototype.getTxHistoryCache = function(walletId, from, to, cb) {