Maybe I'm blind or overlooking it but it looks to me like the "confirm delete" option is no longer available in the stock Email app under General Settings.
Using it with a work Exchange account.
I haven't seen it either. You do get an "undo" option that appears after you click the delete button which is sort of the same thing. I realize it's not exactly the same but it at least gives you an easy way to undo if you accidentally hit delete.