[Exim] Exim/Bogofilter problem

Hello all!

Just thought I'd fire this off here and see if I'm doing anything
stupid with Exim rather than Bogofilter.

Basically, I'm trying to filter my mail using Bogofilter, but it
doesn't work. Exim spews this:

2003-09-01 09:51:25 19tkPF-0001kz-6F == matt@??? R=bogo_router
T=bogo_transport defer (-24): Filter process failure
2003-09-01 09:51:25 SMTP connection from mailnull lost while reading message
data (header)

Every time a mail comes in.. I have no idea why Bogofilter might fail like
that,
and I seem to be able to get absolutely zero output from either apart from
that
line from Exim.

My transport and router are:

# after dnslookup and before system_aliases
bogo_router:
domains = +local_domains
no_verify
condition = ${if !def:h_X-BogoFlag: {true }}
driver = accept
transport = bogo_transport

bogo_transport:
driver = pipe
command = /usr/local/sbin/exim -oMr spam-scanned -bS
use_bsmtp = true
headers_add = X-BogoFlag: true
transport_filter = /usr/local/bin/bogofilter -l -p -e -u -vv -d
/var/bogofilter
return_fail_output = true
group = mail
user = mailnull
home_directory = /tmp
current_directory = /tmp
log_output = true
return_path_add = false


.. as far as I can tell, from every document I have looked at on the web for
this
type of configuration, this is absolutely correct in terms of configuration.

Anyone got any ideas? :)

Thanks in advance..

--
Matt Sealey <matt@???>