How to feed Bayes on relay-only server?

[Thomas Cameron]

Hi all -

I know this has been discussed before, but I wanted to see if anyone had any
recent experiences/advice.

I am going to set up a relay-only server with SA and spamass-milter in front
of my customer's real mail server (big commercial ISP, I can't do anything
with the messages once they are delivered).  We will be changing the MX
record to point to the server I am building then it will pass messages along
to the big ISP.  The big ISP will not be published in DNS as being an MX.

Is there any reasonably easy way to capture ham and spam so as to feed the
Bayesian filter?

I am considering feeding Bayes my personal account's ham and spam but I
can't imagine that will be as helpful as if I could capture all the users'
ham and spam.

Any pointers or suggestions greatly appreciated.
-- 
Regards,
Thomas Cameron