So when you see it's junk you can't be bothered to swipe left and delete?
I have 13,863 unread emails. A lot of it runs deep, far before the iPhone integrated with my email. I don't have the desire to go in and clear them out. When you login to my inbox, the recent pages are clear. But, I just won't go years back to clean things up, lol.
You can, when you get to your desktop, select all and then mark as read.