C DM: Thanks for responding. My query was badly stated. This is my situation.
I have several devices (a PC, a mini iPad with a modern iOS, and this older iPad with iOS version 5.1.1) all sending and receiving Yahoo emails on a common account (common user id and password). In late October the older iPad stopped receiving and sending email messages --- while continuing to work fine in displaying URLs from the internet, downloading , etc.
I was/am asking whether anyone can tell me whether Yahoo (not Apple, as I mistakenly posted) has made some change that now disallows use of Yahoo Mail by iPads with the dated iOS.
If others with older iOS <can still> use Yahoo mail then I will look for other causes of my problem. ---wdc