How can I access an iOS Mail password stored in Keychain? I upgraded my wife's iPhone to a newer model but she can't remember her Yahoo mail password which is stored in Keychain on her old phone.  She uses the standard iOS Mail app which successfully fetches mail from Yahoo on the old phone.  

I've tried syncing the old phone's keychain to iCloud then syncing it back to the new phone using the same process, but with no success.  If I add the Yahoo account on the new phone I am always presented with a blank field for the password.

Should I reset the new phone completely and do a restore from iCloud?

Also I can't use Yahoo's 'forgot password' options on the web because the she also forgot the password to the rescue account.
If you can sucessfully recieve email from your wifes old phone, maybe try restoring the password.