Mark, John -- reading both your messages (and applying significantly more coffee) has induced enlightenment. Yep, this is just not going to work the way I'd suggested. Bad me. No biscuit.
So let me modify these as follows and see if this is any better:
(1) LHS (left-hand-side) rules
Present to list-owner for disposition as done today, but mark it prominently as "noreply address, almost certainly a forgery".
(2) sender rules
Present to list-owner for disposition as done today, but mark it prominently as "probable phish".
Granted, in both cases, the message still has be to processed, but perhaps marking it (both on the "Subject" line and inside the message body) will make it easier/faster for list-owners to deal with.
---Rsk
p.s. As as aside, I strongly recommend against callbacks/SAV. It's inherently abusive, it's a deliberate attempt to bypass site security policies [and thus illegal in some jurisdictions, but ask your attorney for clarification 'cause IANAL], it provides a spam support service, and -- as we've already seen -- it can be used to conduct quite effective DoS/DDoS attacks. And on top of that, far more effective, efficient, and difficult-to-abuse anti-spam methods exist. I'm working [yeah, alright, for some values of "work"] on a "stupid anti-spam techniques" FAQ that will cover this in considerably more depth, so I don't intend this to be by any means a full explanation. However, this topic has been repeatedly discussed on Spam-L in depth, so I'll refer anyone interested to that list's archives until I can manage to get that FAQ cranked out.