Thunderbird 140 released

[Posted July 8, 2025 by jzb]

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.

the Thunderbird project is trying to encourage users to adopt the Release channel for monthly updates instead

Posted Jul 9, 2025 1:41 UTC (Wed) by DeMus (guest, #178252) [Link] (1 responses)

Understandable. But, as you use an immutable distro and therefore Flatpaks from Flathub, like I do, you can only install the ESR version since that is the only flatpak there is. Why isn't there a flatpak from the normal release so people can choose, either the latest or a (more stable?) release which does not get as many updates so it is easier to maintain?

the Thunderbird project is trying to encourage users to adopt the Release channel for monthly updates instead

Posted Jul 9, 2025 7:03 UTC (Wed) by numgmt (guest, #167446) [Link]

I think Thunderbird is interested in making the Flatpak the main upstream Linux package, as they control it and can default its telemetry settings to on. So it's probably something they want to work on.

But the other thing is that Flathub only has Stable and Beta channels for a single package. They would need to create a separate monthly release package or use the Beta channel for monthly releases, which wouldn't be accurate. Having multiple Thunderbird Flatpak packages out there with the only difference being the release channel would be confusing. Would they discontinue the ESR Thunderbird package and only have a stable release package? But then what about users using that?

I guess the only solution right now is having a separate package.

For comparison, Mozilla wanted to make an ESR package for Firefox but never ended up doing so: https://bugzilla.mozilla.org/show_bug.cgi?id=1623591

A user tried to submit Firefox ESR as a Flatpak once. Flathub only objection was that Mozilla wasn't submitting it, so it was rejected: https://github.com/flathub/flathub/pull/3326#issuecomment...

ESR?

Posted Jul 9, 2025 11:01 UTC (Wed) by aragilar (subscriber, #122569) [Link] (1 responses)

I find it a bit odd that Thunderbird is trying to push its ESR users to the normal release channel when presumably they chose that channel for a reason? I wonder if they're trying to drop support for it, and this is some kind of push to make their telemetry reflect what they want to see.

ESR?

Posted Jul 9, 2025 14:28 UTC (Wed) by jzb (editor, #7867) [Link]

They announced the initiative in January. They have only had a Release (monthly) channel since Thunderbird 124, so it's likely many users chose their current channel before the Release channel existed.

I'm guessing that they want to have more people running the monthly to get more regular input on features, and build more "excitement" around Thunderbird's new features that land every month rather than the big bang ESR release that happens once a year. According to the comments, they do not plan to force anyone away from the ESR channel and I don't see any indication it's going away.