sudden influx of old emails into archived mail on iphone 5

Recently, All my old emails have suddenly appeared into my archive folder on my iphone 5. I usually handle unwanted new mails by opening them and pressing the delete button on the bottom of the screen. This action transfers the new mail to the archived folder. I then open the archive folder, hit edit, then manually touch each mail. Then I hit trash all at the bottom of the screen, which transfers them to the trash folder. I then open the trash folder, then hit edit, and press delete all. I don't know how to delete new unwanted mail directly to the trash. Ye gods. I just looked at my trash folder and all the old mails (from the time forward from acquiring my iphone) have moved to the trash folder. I cannot explain this any better. The first thing I thought was that somehow all my email from icloud got migrated to my active phone folders. Can anyone help?

Thanks!