The Yahoo form hasn't worked for a while. When you do get to somewhere for reporting spam, a few hours or days later you'll get a response telling you to submit a report on the exact same form you used. If you do you end up with the same response. Repeat ad infinitum. Same goes for their grey-listing/rate limiting report message. I've given up trying to report anything e-mail related to Yahoo, mostly just apologise to end users and suggest they use another e-mail provider.
I used to use this form semi regularly. It's behavior has changed in
the last couple of months, after i'd finally gotten over the whole 'why
can't I just forward them the email' thing and gotten used to copying
and pasting the header and the body (seperately) into different fields
on their webform.
I'm disgusted that Yahoo (a regular source of spam) no longer readily
offer the means to report the abusers (or abused accounts) in their midst.
This while they apply some of the most over-the-top and disproportionate
justifications to categorise inbound mail as spam (to their customers
detriment, and also their correspondents, who have no idea why they're
being categorised that way).
If anyone knows what Yahoo's intentions are in this space, i'd love to
hear about it.