fix: Added thread data to EXPUNGE command (#783)

Author: jissepo

lib/message-handler.js

@@ -877,7 +877,8 @@ class MessageHandler {
                         ignore: options.session && options.session.id,
                         uid: messageData.uid,
                         message: messageData._id,
-                        unseen: messageData.unseen
+                        unseen: messageData.unseen,
+                        thread: messageData.thread
                     },
                     err => {
                         if (err) {