In “Swipe actions” settings, there should be “confirmation” options for both directions (swipe, then tap to execute) instead of immediately performing the operation assigned to them. Lacking this, it’s far too easy to accidentally mark an email as read/unread, or worse yet delete it.
In addition, to avoid further confusion, it would be better still to eliminate right swiping altogether and instead simply display all assigned actions via a left swipe. This Blue Mail demo image is an example of this behavior, which is much cleaner not to mention safer.