Email Syncing problems Why does my email not sync on my Mac if I have read it on my iPhone or iPad? I can read it in my iPhone or Mac, but it does not show as read on my Mac.
POP does not sync your "read" information (and various other things)

Yahoo does not allow IMAP access, according to the customer response quoted on this link: http://answers.yahoo.com/question/index?qid=20070630193312AAmgjq0