14f6c379_6____Apple_Support_Communities__To_this_
[Do this:] Re-Enter [And use these details:] Choose Mail. Choose Y! Mail (top of the list). Provide your name or your account name in Name. Provide your Yahoo! Mail address—for example, 1234@yahoo.com—in Address. Please make sure to include the @ and the address's domain name, such as @yahoo.com, after the ID. Provide the password for your Yahoo! Mail address. Provide a description of the account. Confirm the settings. [To this:] 
the Yahoo! Mail account in the iPhone
Yahoo mail not pushing with iOS 6? | Apple Support Communities
To this: