It is the Yahoo app from the play store. Interestingly, I found instructions with an option to show notifications in status bar, but that option is now not present. I am finding that I get notifications sometimes. I can check and see none while I do have mail, but on other occasions, it shows a mail icon. This is odd as well as annoying. But the same is happening with my Microsoft Outlook email, which is also inconsistent. Inconsistent is odd, as it means it is not a setting problem, but then what is it?