Welcome to Justanswer.com, my name is ***** ***** I will do my best to assist you.
Lets try a test.. lets download and install the actual yahoo mail app on your iphone.. Once installed, open the yahoo mail app, and try to sign in using your full yahoo email address and password. Will it let you sign in that way and view your mail?
You can get the yahoo app here. https://itunes.apple.com/us/app/yahoo-mail-free-email-and-news/id577586159?mt=8
I strive to provide great service, and greatly appreciate a 5 star rating clicked and submitted when you are satisfied.. I always answer follow up questions.Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.