Thunderbird in taskbar

I’ve tried a long time to find a solution to reduce Thunderbird in Taskbar, like keepass or amarok.
Mozilla added a built-in check box on the windows version, so I assumed the linux version should follow soon. But six month after, still nothing. So, I am searching again.
Does anybody know how to reduce Thunderbird in taskbar ?

Birdtray ?

Works with Thunderbird and Betterbird for me.

I retried Birdtray. I still wasn’t able to make it work : Thunderbird still stay open on foreground.