[Exim] Exim UCE howto?

Hello all,

If google doesn't have one I'm sure one doesn't exist.. but I figured I
would ask anyway.

I'm currently using a program called 'messagewall' (found at
messagewall.org) as an smtp proxy.

It has certain features that I'm wondering if I could (or if they
already are) implemented in exim.

I do have the exim book by Mr. Hazel (3rd chapter is hard read for
newbies imho) but (chapters 4 and 5 make up for it.. )

I see that there are acl filters for each part of the SMTP
'conversation' (chapter 14.8):
acl_smtp_connect
acl_smtp_data
acl_smtp_mail
acl_smtp_rcpt

Is there something some where that has some good spam filtering
techniques for these; either in this book, or online somewhere?

Thanks in advance.

- Brian