Email will not stay deleted

I have 3 different email accounts attached to my Apple mail app - iCloud, Gmail, and my work email. Almost every time I delete an email and I close the app, the emails I just deleted show back up in my inbox as unread, for all three email accounts. I have tried deleted emails all the ways you can delete an email in iOS8, and nothing is working. I have deleted and re-added the accounts multiple times. I've tried everything I know to try. And yes, I regularly update my OS when an update is available. Any assistance would be awesome!

iPhone 5, iOS8