Thanks, you are right, I am on an updated version of BT Yahoo mail.
Why are there 2 BT mail?
How do I get put on BT's own mail rather than the Yahoo version?
BT are in the process, albeit it has stalled for the time being, of moving away from Yahoo to the new BTMail system.
This was meant to be completed prior to the start of this year but as I have said, it has stopped for the time being until some problems are sorted out.
There is no way that you can move or request to be moved onto BTMail, you just have to wait till it happens and nobody seems to know when that will be.
Once the all the email accounts have been migrated BT will severe all connections with Yahoo email.