I just set up Thunderbird on my 14.04 system and I remember seeing an E-Mail icon in the Systems-Tray around a year ago. As I didn't need it, I somehow made it go away.
How do I get an E-Mail Notification Icon for my Systems-Tray to tell me about new Mail?
I've tried the
MinimizeToTray revived extension, which does not give me a Tray Icon (, although I think it does keep it running even if clicking to close, when I enable that feature.)
In addition: How to I set up Thunderbird to start minimized to Tray at startup?