Action on discussion approved

Hi all,

i'm trying to send en email to users who have write a product review… In particular when the review has Approved the system send en email with “Thank you you review has been approved”

Anyone can help me?

I've created a post controller in /addons/my_changes/controllers/admin/discussion.pre.php

in some of this file i should “intercept” the current review modified no? is it the right way?