1. You select a mail message you want to delete.
2. You press the "Delete" button.
3. A new mail message arrives.
4. You click "OK" on the "Are you sure" popup.
Result: Wrong message gets deleted.
Apparently, the system assumes the currently selected mail must be the one the player wanted to delete, because you can't change the selection while the confirmation is up. But the selection will still be automatically changed if a new message arrives, even if the confirmation prompt is up, so that assumption is wrong.
This can potentially result in losing valuable items.
1. Don't change the selection when a new mail arrives.
2. If a new mail arrives while the delete confirmation is up, automatically cancel it.