diff --git a/UI/WebServerResources/js/Mailer/Mailbox.service.js b/UI/WebServerResources/js/Mailer/Mailbox.service.js
index d4e017e8e..36a01699f 100644
--- a/UI/WebServerResources/js/Mailer/Mailbox.service.js
+++ b/UI/WebServerResources/js/Mailer/Mailbox.service.js
@@ -1046,6 +1046,10 @@
                   data.collapsed = true;
                 }
               }
+              else if (!isNaN(data.level) && data.level >= 0) {
+                data.threadMember = true;
+              }
+
             } else {
               data = {uid: msg};
             }