There was a massive Yahoo Mail outage due to Hardware issue. Yahoo Mail was one of the most used mail service by most of the users and this outage results in the problem with mail flow on yahoo services. Some of the internet resources say that there is a very small amount time Flickr was unavailable and then it is resolved.
Yahoo was trying to restore the mail for the users and the report says that most of the users were not able to access their emails since Monday. As a final result, Yahoo provides the status on mail issue in its blog. Yahoo conforms that the problem is solved and about 97% users can access the service without any issue. They have all restored the email queue for the users on the drop of service.
We will update for Outage on Yahoo Mail service