Thunderbird LTS update (78 to 91)

Similarly to what was discussed earlier this year, we have decided to update Thunderbird in all supported Ubuntu releases from 78.x to 91.x. This is a major version update.


Thunderbird 78 is no longer supported by upstream, the last release in the series (78.14.0) having been released over 2 months ago. We don’t expect it to be practical to backport security fixes to LTSes indefinitely. It has therefore become necessary to move to Thunderbird 91.x.

Known downsides

This major new version does bring a number of improvements, UI changes and bug fixes, but we don’t expect any major disruption, unlike in the previous transition from 68.x to 78.x.

One known functional regression is the removal of Movemail support.

Available workarounds

Users of Ubuntu 18.04, 20.04 or 21.04 not wishing to update beyond Thunderbird 78.x may instruct apt to hold or pin the package, but this is not recommended as the package will no longer receive security updates.


This decision was discussed with the SRU team and it was agreed to use the normal security exception process, not the SRU process. It is tracked in bug #1949605 .


Is there a ETA for this update?

No firm ETA, but it is actively being worked on and a high priority. This thread will be updated as soon as packages are ready for wider testing.


and indeed, there is the thunderbird snap which is at 91 already, if you are in a hurry …

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Will binaries for Thunderbird go away as the Firefox ones on later releases?

Not sure what you mean by this?

@oSoMoN He is just asking if Thunderbird package installation will be dropped for snap in future releases.

I guess the question is related to the comment of @ogra. For my opinion both posts have nothing to do with the thread topic.

That’s right, this is a different topic, let’s not derail this thread. I don’t know whether the thunderbird deb will be dropped in favour in the snap in future releases, there’s no firm plan for this as far as I know, and in any case it would be discussed in a separate thread.

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@oSoMoN any news regarding a Thunderbird update for Ubuntu LTS branches? Since the release of 78.14 a lot of “high” rated vulnerabilities have been fixed by newer Thunderbird releases (

I am currently working on validating the update to 91.5.0 with the security team.


And thunderbird 91.5.0 is now available in all supported Ubuntu releases, in the updates and security pockets.


Congrats on all the hard work to get Thunderbird 91 updated! :tada:

I’ve upgraded on Kubuntu 20.04 and everything seems to work flawlessly. The new/improved CardDAV integration is very nice.

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Just an FYI - at least one plugin will make Thunderbird 91 appear broken. I had to go through my plugins to find the culprit and it turned out to be one about hiding local folders - labeled as good for TB78+ but still broke TB.

So, if TB appears broken after the update, be sure to go through your plugins to see if one of those is the culprit.

I meant to mention this yesterday or the day before, but it slipped my mind where the thread was.