This sounds like a configuration issue on your PC, whereby when you click on an email link on Voice or any other website it loads the wrong email client.

I've never used BT Yahoo mail so don't know the specifics of how you set this up, but essentially you want to make BT Yahoo your defailt email program, so that any email links go to this instead of Live Mail.

There is some information here which may be useful. Or you could try contacting BT Yahoo tech support to ask them how to set BT Yahoo mail to be your defailt mail reader.

Thanks

Joe