I've just tried to log in to my email account via BT Yahoo, and been rejected. The reason given is that "The browser you're using refuses to sign in. (cookies rejected)".
Is the stuff at the bottom of this page any use?
The change cookie settings? I've changed mine to 'functional', but won't that only apply to these forums? What I need is something similar for BT Yahoo, but presumably I can only get that once I've loggged in.
I've solved it - and it's not a new problem, it's an old one. I did a google search, and found various postings on forums, going back to about 2007 (on the first page of results - there may be earlier ones).
The problem is caused by 'bt.yahoo' or just 'yahoo' being shown as "block" in a list within internet options. I can only imagine this is caused by them showing up as third party cookies on another website, and thus being blocked.
Tools | Internet Options | Privacy | Sites will take you to a list of 'managed sites', a check showed no 'bt', but a couple of 'yahoos'. I simply removed them, and I can now login to my mail. I also reset my cookie options so that it now asks me whether to block third party cookies.