Found this news story today, http://www.channel4.com/news/yahoos-email-system-hacked-by-criminal-spammers
So it does sound like Yahoo having problems with hackers, but they don't want to admit it?
Yahoo's Twitter https://twitter.com/YahooCare doesn't seem to contain any useful information (nothing you can't find in under a minute with basic Google search).
Lot of Yahoo email users are getting "Suspicious activity was detected on your account" message when they try to send email.
I have Yahoo accounts, as well as Google accounts, and I have been seeing that message for two days now.
Some related recent complaints:
- This one is ironic https://plus.google.com/115106448444522478339/posts/QAmaPZ3z996