ERROR in syncfolder for Gmail

[Simon]

Hi There,

We have been testing using offlineimap (6.3.5-rc1) to sync a gmail mailbox to a local dovecot IMAP mailbox on debian squeeze. I have this rc file setup:

[general]
accounts = Gmail
maxsyncaccounts = 1
ui = basic

[Account Gmail]
localrepository = Local
remoterepository = Remote
autorefresh = 1
quick = -1

[Repository Local]
type = IMAP
remotehost = localhost
port = 143
remoteuser = testlocalaccount
remotepass = test123

[Repository Remote]
type = Gmail
remoteuser = testgmail at gmail.com
remotepass = test123

It was running fine and then i started getting the following: 

yncing [Gmail]/Sent Mail: Gmail -> MappedIMAP
ERROR [<InstanceLimitedThread(Folder sync [Gmail], started daemon -1312851088)>]: ERROR in syncfolder for Gmail folder [Gmail]/Sent Mail: Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/offlineimap/accounts.py", line 321, in syncfolder
    localfolder.cachemessagelist()
  File "/usr/local/lib/python2.6/dist-packages/offlineimap/folder/UIDMaps.py", line 90, in cachemessagelist
    self._mb.cachemessagelist()
  File "/usr/local/lib/python2.6/dist-packages/offlineimap/folder/IMAP.py", line 123, in cachemessagelist
    res_type, imapdata = imapobj.select(self.getfullname(), True)
TypeError: 'NoneType' object is not iterable

  'NoneType' object is not utterable

I cleared out all the email under "[Gmail]/Sent Mail" and it worked again.. the only thing i can think of is that there was an email with "!!!" in the subject line in the mailbox…

Simon