I have two items in my Bulk folder in Yahoo! Mail that Yahoo put there in error. I have selected both of them and clicked the "Not Spam" button, but they stayed in the Bulk folder. So, I selected them again and told it to move them to the Inbox. Nope, they stay in the Bulk folder. Feh. This is why I use Gmail for this kind of work: they do what their users tell them to do.