Connection: add 'update' event for unsolicited, untagged FETCH responses

README.md

@@ -325,6 +325,8 @@ Connection Events
 
 * **deleted**(< _integer_ >seqno) - Emitted when a message is deleted from another IMAP connection's session. `seqno` is the sequence number (instead of the unique UID) of the message that was deleted. If you are caching sequence numbers, all sequence numbers higher than this value **MUST** be decremented by 1 in order to stay synchronized with the server and to keep correct continuity.
 
+* **update**(< _integer_ >seqno, < _object_ >info) - Emitted when message metadata (e.g. flags) changes externally.
+
 * **error**(< _Error_ >err) - Emitted when an error occurs. The 'source' property will be set to indicate where the error originated from.
 
 * **close**(< _boolean_ >hadError) - Emitted when the connection has completely closed.

lib/Connection.js

@@ -1074,6 +1074,8 @@ Connection.prototype._resUntagged = function(info) {
     }
     this._curReq.cbargs.push(box);
    } else if (type === 'fetch') {
+    if (/^(?:UID )?FETCH/.test(this._curReq.fullcmd)) {
+      // FETCH response sent as result of FETCH request
       var msg = this._curReq.fetchCache[info.num],
           keys = Object.keys(info.text),
           keyslen = keys.length,
@@ -1141,6 +1143,11 @@ Connection.prototype._resUntagged = function(info) {
           ended: false
         };
       }
+    } else {
+      // FETCH response sent as result of STORE request or sent unilaterally,
+      // treat them as the same for now for simplicity
+      this.emit('update', info.num, info.text);
+    }
   }
 };