Unread mail count is wrong in iOS7 for Yahoo.
My iOS7 Mail app reports unread messages from my Yahoo account when there are none. The numbers vary from zero to 8, but with the exception of zero, always appear to be more than the actual number. I have tried...
- Checking the configuration of server and client.
- Killing the Mail app.
- Reboot my iPhone.
- Opening every message, read or otherwise.
- Using Edit>Mark All as unread, then Edit>Mark All as read.
- Delete and re-add account.
Occasionally it will report zero as it should, but I've never seen a correct count above zero since I upgraded to iOS7.