If you've updated to IOS 7(GRRRRR) on your ipod/ipad/iphone you may be seeing you have dozens of unread emails in your inbox,even though you know you haven't.
This is a famous Apple glitch that they so far refuse to cure.
All the forums stick to the same line ie "mark all read" only to find it works only for the next email to come in and it's back again. I had 10000 odd from years back.
Here's a solution,it works with Hotmail/Live Mail/Gmail and all web based emails;
Log into your webmail on a computer via your browser,create a folder called,Archive or something like that,highlight all your emails and move them to that box,your inbox will now be empty but you've lost nothing,go to your Apple object and restart it,all your emails will move to that box and now not appear on your phone-unless your last 250 haven't been read by the Apple server,these you can just mark as read on your gadget and it's sorted.
It's taken me 10 days to find this.Thanks Apple I've got better things to do!