diff --git a/offlineimap/folder/Base.py b/offlineimap/folder/Base.py
index 41fd627..b56cd1b 100644
--- a/offlineimap/folder/Base.py
+++ b/offlineimap/folder/Base.py
@@ -236,6 +236,17 @@ class BaseFolder(object):
         You must call cachemessagelist() before calling this function!"""
         raise NotImplementedError
 
+    def msglist_item_initializer(self, uid):
+        """
+        Returns value for empty messagelist element with given UID.
+
+        This function must initialize all fields of messagelist item
+        and must be called every time when one creates new messagelist
+        entry to ensure that all fields that must be present are present.
+
+        """
+        raise NotImplementedError
+
     def uidexists(self, uid):
         """Returns True if uid exists"""
         return uid in self.getmessagelist()
diff --git a/offlineimap/folder/Gmail.py b/offlineimap/folder/Gmail.py
index 2a598de..e3ef92a 100644
--- a/offlineimap/folder/Gmail.py
+++ b/offlineimap/folder/Gmail.py
@@ -110,6 +110,11 @@ class GmailFolder(IMAPFolder):
         else:
             return set()
 
+    # Interface from BaseFolder
+    def msglist_item_initializer(self, uid):
+        return {'uid': uid, 'flags': set(), 'labels': set(), 'time': 0}
+
+
     # TODO: merge this code with the parent's cachemessagelist:
     # TODO: they have too much common logics.
     def cachemessagelist(self):
@@ -152,6 +157,7 @@ class GmailFolder(IMAPFolder):
                                           minor = 1)
             else:
                 uid = long(options['UID'])
+                self.messagelist[uid] = self.msglist_item_initializer(uid)
                 flags = imaputil.flagsimap2maildir(options['FLAGS'])
                 m = re.search('\(([^\)]*)\)', options['X-GM-LABELS'])
                 if m:
diff --git a/offlineimap/folder/GmailMaildir.py b/offlineimap/folder/GmailMaildir.py
index be0d20d..b62b701 100644
--- a/offlineimap/folder/GmailMaildir.py
+++ b/offlineimap/folder/GmailMaildir.py
@@ -56,6 +56,12 @@ class GmailMaildirFolder(MaildirFolder):
                 return True
         return False  #Nope, nothing changed
 
+
+    # Interface from BaseFolder
+    def msglist_item_initializer(self, uid):
+        return {'flags': set(), 'labels': set(), 'filename': '/no-dir/no-such-file/', 'mtime': 0}
+
+
     def cachemessagelist(self):
         if self.messagelist is None:
             self.messagelist = self._scanfolder()
diff --git a/offlineimap/folder/IMAP.py b/offlineimap/folder/IMAP.py
index e317baf..a698888 100644
--- a/offlineimap/folder/IMAP.py
+++ b/offlineimap/folder/IMAP.py
@@ -202,6 +202,10 @@ class IMAPFolder(BaseFolder):
 
         return msgsToFetch
 
+    # Interface from BaseFolder
+    def msglist_item_initializer(self, uid):
+        return {'uid': uid, 'flags': set(), 'time': 0}
+
 
     # Interface from BaseFolder
     def cachemessagelist(self):
@@ -239,6 +243,7 @@ class IMAPFolder(BaseFolder):
                                           minor = 1)
             else:
                 uid = long(options['UID'])
+                self.messagelist[uid] = self.msglist_item_initializer(uid)
                 flags = imaputil.flagsimap2maildir(options['FLAGS'])
                 rtime = imaplibutil.Internaldate2epoch(messagestr)
                 self.messagelist[uid] = {'uid': uid, 'flags': flags, 'time': rtime}
@@ -641,7 +646,8 @@ class IMAPFolder(BaseFolder):
             if imapobj: self.imapserver.releaseconnection(imapobj)
 
         if uid: # avoid UID FETCH 0 crash happening later on
-            self.messagelist[uid] = {'uid': uid, 'flags': flags}
+            self.messagelist[uid] = self.msglist_item_initializer(uid)
+            self.messagelist[uid]['flags'] = flags
 
         self.ui.debug('imap', 'savemessage: returning new UID %d' % uid)
         return uid
diff --git a/offlineimap/folder/LocalStatus.py b/offlineimap/folder/LocalStatus.py
index 7e5928e..1dccf90 100644
--- a/offlineimap/folder/LocalStatus.py
+++ b/offlineimap/folder/LocalStatus.py
@@ -57,6 +57,11 @@ class LocalStatusFolder(BaseFolder):
             os.unlink(self.filename)
 
 
+    # Interface from BaseFolder
+    def msglist_item_initializer(self, uid):
+        return {'uid': uid, 'flags': set(), 'labels': set(), 'time': 0, 'mtime': 0}
+
+
     def readstatus_v1(self, fp):
         """
         Read status folder in format version 1.
@@ -76,7 +81,8 @@ class LocalStatusFolder(BaseFolder):
                     (line, self.filename)
                 self.ui.warn(errstr)
                 raise ValueError(errstr)
-            self.messagelist[uid] = {'uid': uid, 'flags': flags, 'mtime': 0, 'labels': set()}
+            self.messagelist[uid] = self.msglist_item_initializer(uid)
+            self.messagelist[uid]['flags'] = flags
 
 
     def readstatus(self, fp):
@@ -100,7 +106,10 @@ class LocalStatusFolder(BaseFolder):
                     (line, self.filename)
                 self.ui.warn(errstr)
                 raise ValueError(errstr)
-            self.messagelist[uid] = {'uid': uid, 'flags': flags, 'mtime': mtime, 'labels': labels}
+            self.messagelist[uid] = self.msglist_item_initializer(uid)
+            self.messagelist[uid]['flags'] = flags
+            self.messagelist[uid]['mtime'] = mtime
+            self.messagelist[uid]['labels'] = labels
 
 
     # Interface from BaseFolder
@@ -197,7 +206,11 @@ class LocalStatusFolder(BaseFolder):
             self.savemessageflags(uid, flags)
             return uid
 
-        self.messagelist[uid] = {'uid': uid, 'flags': flags, 'time': rtime, 'mtime': mtime, 'labels': labels}
+        self.messagelist[uid] = self.msglist_item_initializer(uid)
+        self.messagelist[uid]['flags'] = flags
+        self.messagelist[uid]['time'] = rtime
+        self.messagelist[uid]['mtime'] = mtime
+        self.messagelist[uid]['labels'] = labels
         self.save()
         return uid
 
diff --git a/offlineimap/folder/LocalStatusSQLite.py b/offlineimap/folder/LocalStatusSQLite.py
index e48545d..a9ef6c2 100644
--- a/offlineimap/folder/LocalStatusSQLite.py
+++ b/offlineimap/folder/LocalStatusSQLite.py
@@ -184,14 +184,23 @@ class LocalStatusSQLiteFolder(BaseFolder):
         self._newfolder = True
 
 
+    # Interface from BaseFolder
+    def msglist_item_initializer(self, uid):
+        return {'uid': uid, 'flags': set(), 'labels': set(), 'time': 0, 'mtime': 0}
+
+
     # Interface from BaseFolder
     def cachemessagelist(self):
         self.messagelist = {}
         cursor = self.connection.execute('SELECT id,flags,mtime,labels from status')
         for row in cursor:
+            uid = row[0]
+            self.messagelist[uid] = self.msglist_item_initializer(uid)
             flags = set(row[1])
             labels = set([lb.strip() for lb in row[3].split(',') if len(lb.strip()) > 0])
-            self.messagelist[row[0]] = {'uid': row[0], 'flags': flags, 'mtime': row[2], 'labels': labels}
+            self.messagelist[uid]['flags'] = flags
+            self.messagelist[uid]['labels'] = labels
+            self.messagelist[uid]['mtime'] = row[2]
 
     # Interface from LocalStatusFolder
     def save(self):
@@ -271,6 +280,7 @@ class LocalStatusSQLiteFolder(BaseFolder):
             self.savemessageflags(uid, flags)
             return uid
 
+        self.messagelist[uid] = self.msglist_item_initializer(uid)
         self.messagelist[uid] = {'uid': uid, 'flags': flags, 'time': rtime, 'mtime': mtime, 'labels': labels}
         flags = ''.join(sorted(flags))
         labels = ', '.join(sorted(labels))
@@ -278,9 +288,11 @@ class LocalStatusSQLiteFolder(BaseFolder):
                          (uid,flags,mtime,labels))
         return uid
 
+
     # Interface from BaseFolder
     def savemessageflags(self, uid, flags):
-        self.messagelist[uid] = {'uid': uid, 'flags': flags}
+        assert self.uidexists(uid)
+        self.messagelist[uid]['flags'] = flags
         flags = ''.join(sorted(flags))
         self.__sql_write('UPDATE status SET flags=? WHERE id=?',(flags,uid))
 
diff --git a/offlineimap/folder/Maildir.py b/offlineimap/folder/Maildir.py
index d067194..156b39e 100644
--- a/offlineimap/folder/Maildir.py
+++ b/offlineimap/folder/Maildir.py
@@ -191,7 +191,9 @@ class MaildirFolder(BaseFolder):
                 else:
                     uid = long(uidmatch.group(1))
             # 'filename' is 'dirannex/filename', e.g. cur/123,U=1,FMD5=1:2,S
-            retval[uid] = {'flags': flags, 'filename': filepath}
+            retval[uid] = self.msglist_item_initializer(uid)
+            retval[uid]['flags'] = flags
+            retval[uid]['filename'] = filepath
         return retval
 
     # Interface from BaseFolder
@@ -208,6 +210,12 @@ class MaildirFolder(BaseFolder):
                 return True
         return False  #Nope, nothing changed
 
+
+    # Interface from BaseFolder
+    def msglist_item_initializer(self, uid):
+        return {'flags': set(), 'filename': '/no-dir/no-such-file/'}
+
+
     # Interface from BaseFolder
     def cachemessagelist(self):
         if self.messagelist is None:
@@ -319,7 +327,9 @@ class MaildirFolder(BaseFolder):
         if rtime != None:
             os.utime(os.path.join(self.getfullname(), tmpname), (rtime, rtime))
 
-        self.messagelist[uid] = {'flags': flags, 'filename': tmpname}
+        self.messagelist[uid] = self.msglist_item_initializer(uid)
+        self.messagelist[uid]['flags'] = flags
+        self.messagelist[uid]['filename'] = tmpname
         # savemessageflags moves msg to 'cur' or 'new' as appropriate
         self.savemessageflags(uid, flags)
         self.ui.debug('maildir', 'savemessage: returning uid %d' % uid)
@@ -339,6 +349,9 @@ class MaildirFolder(BaseFolder):
         Note that this function does not check against dryrun settings,
         so you need to ensure that it is never called in a
         dryrun mode."""
+
+        assert uid in self.messagelist
+
         oldfilename = self.messagelist[uid]['filename']
         dir_prefix, filename = os.path.split(oldfilename)
         # If a message has been seen, it goes into 'cur'