I've tried something similair to this only with automated RBL via mail forwarding to a single adres like
spam@domain.comWhat I found out is that AMS does not yet support you extracting anything from inbound mails and doing something with it. I always take the time to mail support about these things since Code Crafters has implemented almost everything I ever had the idea to suggest to them.
From the reply on my latest mail:
I should note that we also have considered how content filtering could be designed to obtain specific custom strings from the mail body and headers. This means that in a future update there is a good chance we may introduce something to do just this.
I'm not sure this will help in any way on the Bayesian filter, my novel way of dealing with the Bayesian filter is to let people use IMAP4 and created two permanent serverside included folders SPAM & NON-SPAM incase something is read wrong. Every 24 hours my server automatically scans the SPAM folder for content and I just set up a simple mail adres to allow users to mail me when Bayesian filterd something out they deffinatly don't want filterd out.
But for a more usuable filter I highly recommend using a simple DNS server to create your own RBL. It's fairly easy to script the means to add a DNS record via a simple webapplet using something like PHP.
EDIT: Note that it is advisory to inform your users that when using IMAP4 over the normal port that their username and password is send as plaintext over the internet to your server, if you need to provide a secure envoirment you should deffinatly considder using the SSL version of IMAP4.