[exim] Redirect SPAM

Hi,

We would like to start dropping spam in special maildir folders. For
instance a folder Low-Spam and a
folder High-Spam where accordingly spam will be dropped with a low rating
and a high rating.

I've googled and all it came up with was examples how to do this with
.forward files. And I really would
like to use some kind of exim config for this instead of .forward files in
homedirectories (which most users
don't have anyway).

As I have not much experience in creating routers/drivers/transports for
these kind of things could
someone give me pointers on how the best way is to do this? Should I flag
spam and then use a router
with a condition to send it to an appropiate transport for instance?

Gladly appreciated if someone could give me a hint on how to do this.

Sincerly,
Pascal