Survival Tips for Yahoo's New Anti-Spam Policies?

skagin asks: "Yahoo has instituted a new set of anti-spam policies which are causing havoc for our customers (we're a small ISP). List mail with non-existant, over-quota, or recently cancelled recipients is being bounced whole, and much of the one-to-one mail we send is bouncing. Yahoo tells us that our mailserver is being treated as suspicious because of the number of bad recipients being sent to, but most of those are bounces from yahoo spam sent to non-existant addresses on our network. Our customers are going nuts. Is anyone else out there having this problem with Yahoo?"