http://helpforum.sky.com
"Sky Yahoo! Mail
We are aware of an issue affecting Customer's access to the Sky Yahoo! Email service.
We are working tirelessly in order to resolve the issue and restore full service.
In the interim you can access your Sky Yahoo! Mail account direct via :
www.yahoo.com
To access your account enter your full Sky Email address (including @sky.com) and your associated Password
We apologise for any inconvenience caused and will provide an update as soon as possible"