There is a setting for the emails to delete them on the servers when you delete them on your devise. Otherwise, it will always think you have new emails when checking as it's doing now.
Good Luck!
Sent from my iPhone 5 using Tapatalk.
My Yahoo and Gmail both kept doing this. All I did was delete both email accounts from the built in email application and re-installed them. It works perfectly now. I did not need to do any factory reset.
Sent from my Samsung Galaxy Note 3.