I've been having SERIOUS problems with Yahoo! mail in the last 24 hours. I pay extra money for their POP service. But some kind of wonky message got stuck in Mail.app on OS X and I'm pretty sure the problem is Apple's. Almost as soon as I had that working again, though, suddenly I started having trouble accessing my Yahoo mailbox, even through the web interface. I just couldn't download my messages. I've been getting partial downloads as well. It's really annoying.
I wish I knew someone who works at Yahoo. If I have trouble with Apple or Google I can just pick up the phone and start bitching to someone in the know. But not with Yahoo.
The problem is on-again, off-again and seems to coincide with failures to access on the web sometimes, like just now. I think this is Yahoo's fault.