I used to have an extension or add-on the allowed me to play my own sounds for an incoming email on Thunderbird. However, that seems to have disappeared and I cannot find an add-on that will allow me to to that. I have many sounds that used to work but whenever you do an update to the browser they don't work.

Is there any add-on that you have that will work with my own alerts on Thunderbird or do I need to find another browser?