We were both smacked as kids too, and believe that a smack is ok when it is controlled. We have set limits like only with hand, only 1 or 2 at a time and things like that. We have also found with DD1 (who is 3 so it might work with your DD now) that confiscating her favourite dolly works very well, and is often more effective than a smack. She will eventually learn that her actions have consequences, so do give her 3 chances and make sure you follow through on what you threaten her with.