As of today, Yahoo mail won't push mail from my Yahoo account to either my iPad or my iPhone. I can open the mail app and manually refresh to get new mail, but mail won't push on it's own. I tried the basic trouble shooting steps of removing my Yahoo account from my iPhone and iPad and re-added and also turning push off and on, neither fixed the problem.
I wanted to see if it was a global problem so I created a dummy Yahoo account and added it to my iPhone and push worked for that account, so I know push is working. Now here's the weird part. When I added the dummy Yahoo account to my iPhone, push started working for my actual account. I repeated this with my iPad and it worked there as well.
Thinking things were fixed I removed the dummy Yahoo account and push stopped working on my real account. I added the dummy account back in and push started working for my real account. So basically I need to have a dummy Yahoo account on devices to get push mail to my real account. The opposite is not true, I can delete my real account and the dummy account will still get push mails. I tried leaving the dummy account on the phone, but turning mail off, but that too causes my mail account to stop receiving push notifications.
It looks like when a Yahoo account is added to an iOS device, a message is sent to Apple's push servers indicated the Yahoo email address that was added. Similarly when an account is removed a message is sent to indicate the email account was removed. That way Apple knows if any Yahoo Mail accounts are on the phone and if there aren't any it won't push. That or it can tell Yahoo that there are accounts on the phone that need push email.
At this point I don't know how to get things working without using my work around. I can tell the iPhone/iPad is sending info to Apple when I add my main Yahoo account to the device, but the push to check for new messages isn't coming in unless I add a different Yahoo account to the devices and turn mail on.
Anyone know how to fix this?