You should definitely contact the postmasters for some of the major
consumer ISPs -- they often have their own filtering policies and
procedures. AOL's policies have been discussed on this list in the
past. Also watch out for Earthlink's challenge/response scheme.
--Steve Bellovin, http://www.research.att.com/~smb (me)
http://www.wilyhacker.com (2nd edition of "Firewalls" book)