[Exim] Most efficient spam rejection with Bogofilter

Just wondering what the most efficient/successful way is to
reject Spam once it has been evaluated by Bogofilter?

At the moment it just hits my inbox and my mailer or sieve
scripts (using Cyrus IMAP here for remote access) just junk
it into a Spam folder like Hotmail and delete it after 7
days if I don't check for false positives.

Since I have run a few thousand mails through and it's not
got one wrong yet, I'd rather forget receiving the Spam and
just delete it right there and then - either drop it
entirely or do something else with it.

Anyone got any ideas on this? Should I just scan the
header for "X-Bogosity: yes" and match, or can I do it
on the severity too, somehow? Or can I do it on the
output of the bogofilter filter (it returns a certain
number for spam or ham)? Anyone got any short examples
that works for them?

--
Matt Sealey <matt@???>