On SPAM-L, Steven Champeon mentioned the following paper:
http://www.ceas.cc/papers-2005/176.pdf
Here is the abstract. I haven't read the entire paper, but what I
have read looks very promising.
Abstract
Most proponents of domain authentication
suggest combining domain authentication with
reputation services. This paper presents a new
learning algorithm for learning the reputation
of email domains and IP addresses based on
analyzing the paths used to transmit known
spam and known good mail. The result is an
effective algorithm providing the reputation
information needed to combine with domain
authentication to make filtering decisions.
This algorithm achieves many of the benefits
offered by domain-authentication systems,
black-list services, and white-list services
provide without any infrastructure costs or
rollout requirements.
-wayne