It appears to be applied correctly. What are you using as the FROM address for the email? Who is your hosting provider? Can I see a copy of the page: webassist/email/waue_confirm_10.php
I think the next step is to look in the session after sending the email. We store the send results there and it can be telling. Create a new blank page and put this on it:
Then, after checkout, browse that page and see the contents. It will tell you whether it thinks the email was sent or not and may give an error message. View source on that page and send me the results and I can help interpret it..