I followed this tutorial to set start Thunderbird in minimized mode at startup, but it wasn't helpful.

After following the instructions, I could not even start Thunderbird. So I was forced to start TB in safe mode to delete the "FireTray Plugin" and fix this issue. After that it started to work but it deleted all my email accounts and I had to do that chore all over again .

So is there any working way to start Thunderbird minimized on start-up?