Python Error with Postfix queue filling up

I noticed that some emails were not comming through on my Kolab 3 
server. The mail logs filled up with entries such as this:

postfix/smtp[12133]: AA3861280D28: to=<[email protected]>, 
relay=127.0.0.1[127.0.0.1]:10026, delay=377952, delays=377952/0/0/0, 
dsn=4.4.2, status=deferred (lost connection with 127.0.0.1[127.0.0.1] 
while sending end of data -- message may be sent more than once)

It seems that most emails are coming through, but there are about 11 of 
them in the queue that aren't moving. After some troubleshooting, I 
restarted the Wallace service and then started getting this error for 
every stuck message on the console when I try to flush the queue:

# error: uncaptured python exception, closing channel 
<smtpd.SMTPChannel connected 127.0.0.1:44624 at 0xa320b0c> (<type 
'exceptions.UnicodeDecodeError'>:'utf8' codec can't decode byte 0xbb in 
position 10277: invalid start byte 
[/usr/lib/python2.6/asyncore.py|read|78] 
[/usr/lib/python2.6/asyncore.py|handle_read_event|428] 
[/usr/lib/python2.6/asynchat.py|handle_read|158] 
[/usr/lib/python2.6/smtpd.py|found_terminator|184] 
[/usr/lib/python2.6/site-packages/wallace/__init__.py|process_message|249] 
[/usr/lib/python2.6/json/__init__.py|dumps|230] 
[/usr/lib/python2.6/json/encoder.py|encode|367] 
[/usr/lib/python2.6/json/encoder.py|_iterencode|309] 
[/usr/lib/python2.6/json/encoder.py|_iterencode_dict|275] 
[/usr/lib/python2.6/json/encoder.py|_iterencode|294])

Can anyone enlighten me on what going on? This python error is beyond 
me.
-- 
Mat