Hi, 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.
It still works, but needed "Disable Add-on Compatibility Checks" extension to bypass version compatibility. Could you please update your "DSN settings" addon to make it officially compatible with Thunderbird 45, thanks!