At 8pm the mail started to download on third party apps on Windows and iOS devices. Good work by the teams working on it, but a lot of people are frustrated after being given incorrect advice by @yahoocare on Twitter
Service Status now marks the BT Yahoo mail problem as resolved,
BT Yahoo Mail issues
Time resolved:Sat 28/02/2018 at 20:33
We have now fixed the issue which stopped some customers from being able to log into their BT Yahoo email by an app or client. We're sorry for any inconvenience this may have caused.
And I have no idea why the service status message gives the date of resolution as 28/02/2018, just glad things seem to be working as they should.
This problem has occurred at the weekend and all weekend for the past two weeks.