Yahoo does process the mail sent to:
abuse@yahoo.com
Everyone should report abuse to them.
I don't have time to report spam one by one. We reject 1.2 million a day and still get 2,000 spam reports a day. I would implement something automated. We look up URL hostnames in SURBL, URL IP addresses in Spamhaus, and under consideration now is looking up PTR for the IP and scoring as possible spam if it points to yahoo. The only question weighing how useful that test would be against the time to do DNS lookup.
Joseph Brennan Columbia University Information Technology