It said there are 3 unread e-mails on my ipad, but when i checked all of my e-mail i found nothing is unread. How could i solve this?

Hey Rdr3ds,

Thanks for the question. To troubleshoot this issue, I'd like you to temporarily create the "Unread" favorite mailbox:

Make a favorite mailbox. Favorites appear at the top of the Mailboxes list. To add one, tap Edit while viewing the Mailboxes list. Tap Add Mailbox, then select the mailboxes to add. You’ll also get push notifications for your favorite mailboxes.

When creating a favorite mailbox "Unread" will be an option. After adding this mailbox, check to see that there are not any unread emails.

See important messages - iPhone User Guide

http://help.apple.com/iphone/7/#/iph3caefa61

Thanks,

Matt M.