I love this add-on, would be even more happy, if it would work. Rated 4 out of 5 stars

I installed the latest version yesterday, sadly do not receive any delivery notifications.

Your SMTP server does not support DSN

This add-on only adds UI settings for sending DSN.
If you do not receive any notifications, it's probably because your SMTP server does not support DSN.
In order to check that, create a telnet connection to port 25 of your SMTP server and type "ehlo test". The server should answer "250 DSN" if it provides DSN.