Just like what people asked here in the past (How to run Thunderbird in the background?, Start Thunderbird in background), I would like to have Thunderbird running at all times during which my PC is turned on and notify me of new e-mails.
In the past, many suggested FireTray, which is not available for Thunderbird >50.
What would be your best workaround?
I have Ubuntu 16.04/Thunderbird 52.
Related: Thunderbird 60.2.1 "MinimizeToTray revived" add-on stopped working
You can actually still use FireTray even though it's not officially supported for Thunderbird v52.
Open your web browser, go to the add-on's homepage, and download the add-on by clicking the "Download for Linux" button.
Then launch Thunderbird and open Add-ons Manager. Click on the button with a cogwheel, select "Install Add-on from File", and install FireTray from the downloaded file.
Alternatively, just launch Thunderbird and drag & drop the the downloaded file over the Thunderbird window to install the add-on.
Warning: Try this at your own risk. Since the FireTray project is discontinued you may get no support if it breaks something. (I'm using FireTray with Thunderbird 52 without any issue.)
You can add it as startup application. Put
/usr/bin/thunderbird --headless
to the command field and restart. Headless option runs Thunderbird without GUI.