The team behind the open source Thunderbird email client plans to introduce a change in version 154 that changes the default minimize and close behavior on Windows.
Currently, when you close Thunderbird on Windows, the program exits and stops running in the background. When you hit the minimize button, Thunderbird lands in the System Tray area.
Starting in Thunderbird 154, this behavior changes to the following:
- Minimize: When you activate the button, Thunderbird’s window is minimized, but no longer moved to the System Tray.
- Close: This can be set to minimized to the System Tray and is the default on systems that use the “When Thunderbird is minimized, move it to the tray” preference already.
Thunderbird users may enable “close to tray” to make sure the email client continues to run when the close button is activated. You find the option under Menu > Settings > General > System Integration > When Thunderbird is closed, move it to the tray.
The team says that the option is disabled by default. Users who want the new behavior need to enable the option. There is also an option to start Thunderbird minimized in the System Tray. You find it under System Integration > Start Thunderbird in the tray.
Thunderbird 154’s release date is set to August 18, 2026. It may already be available in some of the development channels.