I just updated to iOS 5.0 on my iphone and when it started up for the first time, all of my emails in a POP account are now showing as unread. The total is 79 emails and I don't want to go one at a time marking each one as read. Is there a way to do it in one sweeping motion?
I'm afraid ughoavgfhw gave you the answer. It's a "feature" in iOS 5.
But if you work with GMail, it's easy. Go to your browser, check them all and set them on read. If you've enabled push on your iPhone, the mails will be marked as read on your iPhone as well!
Check out this link for a better option. http://www.youtube.com/watch?v=CmaqzeXfO5s