[Spambayes] Error on review page

[David Shaw]

I've been using spambayes for a few weeks and have been very impressed. 
  I have even started a real GUI to emulate the functionality of the Web 
interface.

Anyway, on to my problem.  I got a lot of mail today (partially from 
joining this list), and when I go to the review screen now I see this:

500 Server error
Traceback (most recent call last):

   File "spambayes/Dibbler.py", line 398, in found_terminator
     getattr(plugin, name)(**params)

   File "./pop3proxy.py", line 916, in onReview
     message = mboxutils.get_message(cachedMessage.getSubstance())

   File "spambayes/Corpus.py", line 344, in getSubstance
     return self.hdrtxt + self.payload

   File "spambayes/Corpus.py", line 291, in __getattr__
     raise AttributeError, attributeName

AttributeError: hdrtxt

I suspect that the problem is one of the mbox files where messages are 
cached got corrupted.  Any thoughts on where to chase this down?  Also, 
assuming I do, should there be some more robustness in the code to 
handle such problems if they do happen?