Thunderbird 140 released

Version
140 of the Thunderbird mail client has been released. Notable
features include 'dark message mode' to adapt message content
to dark mode, the ability to easily transfer desktop
settings to the mobile Thunderbird client, experimental support for
Microsoft Exchange, as well as global controls for message threading
and sort order.

Thunderbird 140 is an extended-support
release (ESR) which will be supported for 12 months. However, the
Thunderbird project is trying to encourage users to adopt the Release
channel for monthly updates instead. The project is staggering
upgrades to 140 for existing Thunderbird users in order to catch any
significant bugs before they are widely deployed, but users can
upgrade manually via the Help > About
menu. See the release
notes for a full list of changes.