Yeah, that's what I thought at first also. But I have sent and deleted e-mails and the folders still don't show up. I think it might have something to do with the e-mail settings because I added an imap path prefix which seemed to get the push to work but I think it removed all the folders.
The yahoo email services seems to be really spotty for me. Sometimes it's push, sometimes it's not. I've also sent emails that never went out.