I tested this script by permanently deleting email in Entourage then going to the database file and opening it with text edit and searching for the email. It is still in the database. Then I did another test of deleting another email, then rebuilding the database, then searching it and still found the email. Last test, delete an email, and advanced rebuild repair on the database and then ran it through text edit and still found the email.
CONCLUSION: this script is a complete joke! Don't waste your time!