diff --git a/lib/message-handler.js b/lib/message-handler.js
index 9fc1e9f2..d8516cd3 100644
--- a/lib/message-handler.js
+++ b/lib/message-handler.js
@@ -1090,6 +1090,7 @@ class MessageHandler {
                 )
         );
 
+        subject = this.normalizeSubject(subject, { removePrefix: true });
         referenceIds = Array.from(referenceIds).slice(0, 10);
 
         // most messages are not threaded, so an upsert call should be ok to make