Sberman, this does not answer my question. let me rephrase it: (This is a "settings" issue, not a Yahoo App issue.)
So, on my iPhone 7Plus, with iOS 10.2.1 - I go to SETTINGS, then scroll down to MAIL, then ACCOUNTS. In accounts there is a list of emails I have added to my phone. There's Yahoo, Gmail, and the obligatory iCloud mail
(which I never use). At the bottom of this page it says "FETCH NEW DATA PUSH" Ok. Now I click on the word "push" and it takes me to the next page of options. On the top it says "Push" which has a toggle for on & off. IT IS ON. Below that is another list of my registered email accounts and an option next to each one of them. THE iCloud EMAIL ACCOUNT IS THE ONLY ONE THAT HAS THE OPTION TO SELECT "PUSH"!!! All the others give the options of either a "fetch" or "manual" schedule. MY QUESTION SHOULD HAVE BEEN, "WHY IS ICLOUD EMAIL THE ONLY ONE WITH THE "PUSH" OPTION? Yes, Yahoo is my default email...it is in settings that my question applies. The answer maybe should come from Apple? There is no push OPTION in the settings for any email except iCloud. Did I miss something with the last update?