Whenever I receive a Yahoo! e-mail message on my iPhone 5 (running 6.0.1) I hear the default "ding" even if the phone is on vibrate and I have it set not to play sounds when receiving mail. It is only Yahoo! Mail. My corporate e-mail (pushed through a MobileIron server) and other e-mail accounts (that are fetched) don't do this. This seems to have started yesterday and I can't figure out why. I've tried everything I can think of. I've reset all settings, done a cold boot, deleted Yahoo! and reinstalled it, and even did a clean restore. Nothing has worked so far. Any ideas? This is getting really annoying.