When I delete sent emails they go to the deleted folder (this is great) - when i delete emails from my inbox they simply vanish. How can I make my inbox emails show in the delete folder the same as the sent ones?
I'd say it depends on your servers retention policies, what sort of account you are using, how you are connecting, where the data is stored, how you are deleting etc.. if you just push del, it should be moved to deleted items, if you press shift+del it should be gone. However, it might be retained in the "Recover Deleted Items" tools menu, at least until the next backup/scavange cycle (assuming exchange).
This question might be better on SuperUser..