diff --git a/pymap/msgtracker.py b/pymap/msgtracker.py
new file mode 100644
index 00000000..d16dab36
--- /dev/null
+++ b/pymap/msgtracker.py
@@ -0,0 +1,66 @@
+# Copyright (c) 2014 Ian C. Good
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
+
+import asyncio
+
+__all__ = ['MessageTracker']
+
+
+class MessageTracker(object):
+
+    def __init__(self):
+        super().__init__()
+        self.messages = {}
+        self.exists = 0
+        self.recent = 0
+
+    @asyncio.coroutine
+    def update(self, messages):
+        """Given a list of messages, return a new tracker and a dictionary of
+        external updates that need to be returned in untagged FETCH responses.
+
+        :param list messages: :class:`~pymap.interfaces.MessageInterface
+                              objects fetched from the backend.
+        :returns: Two-tuple of the :class:`MessageTracker` object and details
+                  about what has changed since the last :meth:`.update`.
+
+        """
+        ret = {}
+        if self.exists != len(messages):
+            ret['exists'] = self.exists = len(messages)
+        uid_flags = {msg.uid: (msg.seq, (yield from msg.fetch_flags()))
+                     for msg in messages}
+        recent = len([True for _, flags in uid_flags.values()
+                      if br'\Recent' in flags])
+        if self.recent != recent:
+            ret['recent'] = self.recent = recent
+        before_uids = frozenset(self.messages.keys())
+        after_uids = frozenset(uid_flags.keys())
+        ret['expunge'] = [self.messages[uid][0]
+                          for uid in (before_uids - after_uids)]
+        ret['flags'] = []
+        for uid in before_uids & after_uids:
+            before_flags = frozenset(self.messages[uid][1])
+            after_flags = frozenset(uid_flags[uid][1])
+            if before_flags != after_flags:
+                seq = uid_flags[uid][0]
+                ret['flags'].append((seq, after_flags))
+        return ret
diff --git a/pymap/state.py b/pymap/state.py
index f1fb6054..a40276c3 100644
--- a/pymap/state.py
+++ b/pymap/state.py
@@ -61,6 +61,7 @@ def __init__(self, transport, backend):
         self.backend = backend
         self.session = None
         self.selected = None
+        self.tracker = None
         self.capability = Capability([])
 
     @asyncio.coroutine
@@ -113,7 +114,7 @@ def do_select(self, cmd):
         except MailboxNotFound:
             return ResponseNo(cmd.tag, b'Mailbox does not exist.')
         self.selected = mbx
-        yield from mbx.poll()
+        self.selected_tacker = yield from mbx.init()
         code, data = self._get_mailbox_response_data(mbx)
         resp = ResponseOk(cmd.tag, b'Selected mailbox.', code)
         for data_part in data:
@@ -127,7 +128,7 @@ def do_examine(self, cmd):
         except MailboxNotFound:
             return ResponseNo(cmd.tag, b'Mailbox does not exist.')
         self.selected = mbx
-        yield from mbx.poll()
+        self.selected_tacker = yield from mbx.init()
         code, data = self._get_mailbox_response_data(mbx, True)
         resp = ResponseOk(cmd.tag, b'Examined mailbox.', code)
         for data_part in data:
@@ -176,7 +177,7 @@ def do_status(self, cmd):
             mbx = yield from self.session.get_mailbox(cmd.mailbox)
         except MailboxNotFound:
             return ResponseNo(cmd.tag, b'Mailbox does not exist.')
-        yield from mbx.poll()
+        yield from mbx.init()
         resp = ResponseOk(cmd.tag, b'STATUS completed.')
         status_list = List([])
         for status_item in cmd.status_list:
@@ -254,6 +255,7 @@ def do_close(self, cmd):
         except MailboxReadOnly:
             pass
         self.selected = None
+        self.tracker = None
         return ResponseOk(cmd.tag, b'CLOSE completed.')
 
     @asyncio.coroutine
@@ -373,7 +375,7 @@ def do_logout(self, cmd):
     @asyncio.coroutine
     def _check_mailbox_updates(self, cmd, resp):
         send_expunge = not getattr(cmd, 'no_expunge_response', False)
-        updates = yield from self.selected.poll()
+        self.tracker, updates = yield from self.selected.poll(self.tracker)
         if 'exists' in updates:
             resp.add_data(ExistsResponse(updates['exists']))
         if 'recent' in updates:
@@ -381,10 +383,10 @@ def _check_mailbox_updates(self, cmd, resp):
         if 'expunge' in updates and send_expunge:
             for seq in updates['expunge']:
                 resp.add_data(ExpungeResponse(seq))
-        if 'fetch' in updates:
-            for msg in updates['fetch']:
-                fetch_data = yield from msg.fetch([self.flags_attr])
-                resp.add_data(FetchResponse(msg.seq, fetch_data))
+        if 'flags' in updates:
+            for seq, flags in updates['flags']:
+                fetch_data = {self.flags_attr: List(flags)}
+                resp.add_data(FetchResponse(seq, fetch_data))
 
     @asyncio.coroutine
     def do_command(self, cmd):