My iphone5 is not updating my yahoo email. I can send emails using yahoo from my phone but it will not update with new incoming emails. I have turned off the device, waited and turned it back on to no avail. I have "rebooted" by pressing the sleep button and the wake button at the same time. I have deleted my yahoo email and re-added yahoo email. The phone still says updated Sunday on the yahoo email. My other email accounts are working correctly. Suggestions please.