diff --git a/addons/mail/static/src/models/attachment_viewer.js b/addons/mail/static/src/models/attachment_viewer.js
index 80e032e39b0..53ac42f679e 100644
--- a/addons/mail/static/src/models/attachment_viewer.js
+++ b/addons/mail/static/src/models/attachment_viewer.js
@@ -6,6 +6,7 @@ import { clear } from '@mail/model/model_field_command';
 
 registerModel({
     name: 'AttachmentViewer',
+    identifyingMode: 'xor',
     recordMethods: {
         /**
          * Close the dialog with this attachment viewer.