My own yahoo account does not require domain key authentication, but new yahoo accounts do. I believe yahoo is forcing this "technology" on all yahoo mail users soon.
If BIS 2.0 w/ yahoo integration works some, great! I created a new yahoo mail account and then tried to send emails from my BB w/ yahoo integration and they were rejected. I sent more messages from my
BIS account and they went through fine.
To make sure all of my emails get through, I've started to send them with my blackberry.net account.