Any non-contactable blacklist should not be taken serious. Posting to a public forum (ie usenet) to contact the maintainer of such is list is not acceptable and I for one can not understand why any responsible site administrator would use such a list.
I've always had the impression that SPEWS did this to make legal action difficult. Many of the other RBL, ORB, are targets of legal action. If it is difficult to contact "them" how does one pursue the matter? SPEWS has no due process procedure for handling issues and the flip side of that is that there is no clear-cut process for dealing with them legally either. I would guess that by "raising the bar" for their responsibility they are also, ultimately, setting themselves up for a larger action, perhaps even under RICO. I see them as some kind of amorphous SPAM militia. Responsible, overloaded administrators might. IMHO blacklists should always be local to the organization. Anything else is to abdicate responsibility for the result because what constitutes SPAM is a subjective judgment. (analagous to what constitutes pornography.) -John