Yahoo will no longer support Yahoo Mail in the built-in iOS mail app for devices running iOS 4 and older. Support for Mail and Contacts syncing on older Mac and iOS devices will be discontinued after June 15.
“In order to maintain focus on the security, speed and functionality of Yahoo Mail on the latest systems, we are no longer supporting Yahoo Mail on the built-in Mail app for devices prior to iOS 5 on June 15, 2015. If you use iOS 4 & earlier, you can continue to use Yahoo Mail on their Safari mobile browser at mail.yahoo.com “
posted Yahoo in a company blog.
If you use Yahoo Mail through the stock Mail app on an iOS 4 device or earlier, you will not be able to access Yahoo Mail through Apple Mail come June 15. Yahoo Mail will only work with Apple’s built-in Mail app on iPhones, iPads, and iPod touches running iOS 5 or later. Yahoo will even shut down a number of other services including maps.yahoo.com, but will continue to support maps on Yahoo Search and on several other properties including Flickr.
In case of contacts, Yahoo will no longer support contact syncing on systems running OS X Lion 10.7 or earlier to address security and speed concerns.