I added my yahoo account by doing the email setup. In my yahoo account I have different folders that I have assigned specific emails to go to. I receive emails on my BB that go to my general inbox, but those that are sorted to a specific folder I don't get on my BB.
So I'm not receiving all my emails from my yahoo account to my BB.
I am not a Yahoo user, but given experience with similar email apps and also from reading about Yahoo in BBF, my guess is that the mail is going to the folders before it can be pulled by RIM and pushed to your device.
__________________ The difference between stupidity and genius is that genius has its limits. When you take things for granted, the things you are granted, get taken. Even a mosquito doesn't get a pat on the back until it starts to work. Too many people miss the silver lining because they're expecting gold. [BES 5.0.3 / GroupWise 2012 HP2]