Thunderbird 78.3.1 released, here are the changes

The team behind the Thunderbird email app has released version 78.3.1. The release is notable for a number of OpenPGP improvements, and for general fixes and reliability issues.


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Thunderbird is my preferred email client of choice. I use this app on every PC and on every operating system I use. It is stable, contains all the features you need, supports add-ons and also comes with a useful RSS reader. I am using Thunderbird for many years and never felt the need to look for an alternative.

Thunderbird 78 doesn't support classic XUL add-ons any more, but includes some of their features natively. E.g. on Windows you can minimize the app to the system tray.

It is worth noting that initially MZLA Corporation released Thunderbird 78.3.0, but quickly released version 78.3.1, as the previous one caused the application to crash after the user upgraded to it. The following changes have been made in versions 78.3.1 and 78.3.0.

Thunderbird 78.3.1 changes


Thunderbird crashed after updating to 78.3.0

Fixes arrived in version 78.3.0

  • Selecting "Cancel" on the Master Password prompt at startup incorrectly reported corrupted OpenPGP data
  • OpenPGP: Creating a new key pair did not automatically select it for use
  • Dragging & Dropping recipient pills resulted in lost pills when an error was present
  • Spellcheck suggestions were unreadable in dark theme
  • Calendar: Multiple password prompts opened
  • Linux Distributions: UI was not rendered completely when built without updater
  • MailExtensions: browser.folders.delete failed on IMAP folders
  • Various security fixes


  • OpenPGP: Improved decryption performance with large messages
  • OpenPGP: Do not show external key UI when disabled by preference
  • Account setup wizard will now open a popup when connecting to a server with a self-signed SSL/TLS certificate
  • Installation of "legacy" MailExtensions now disabled
  • Reply-To header moved in compose window; now appears under From header
  • Calendar: Sidebar UI improvements

Knows issues

  • Message list is not focused at startup

Download Thundebird

Download Thunderbird

The release notes are available here.

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Author: Sergey Tkachenko

Sergey Tkachenko is a software developer who started Winaero back in 2011. On this blog, Sergey is writing about everything connected to Microsoft, Windows and popular software. Follow him on Telegram, Twitter, and YouTube.

3 thoughts on “Thunderbird 78.3.1 released, here are the changes”

  1. I have a question. Does anyone else have a delay when creating a new message (or replying, forwarding etc.) I get one and the consensus on the Mozilla forums was that it was the fault of the 2004 update. Anyone else with the issue?

  2. Thanks Sergey.

    I too love Thunderbird but was very disappointed by the quality of version 78 when it auto updated recently.

    Often, my auto mark messages read after 2 seconds don’t work anymore. Messages stay unread. It feels like some stuff is going on in the background and TB forgets to finish what it started.

    It is not easy to add a cc recipient using the keyboard and not the mouse. It is an annoying combination of keys for something that we do all the time in an office setting. Same thing for bcc. Those need a short keyboard shortcut at the very least. Also, for newbies, having a flat cc button somewhere on the right make it much less user friendly than the previous way it worked. The buttons should be on the left next to From and To fields. You leave an empty line with only the button so if you type the name, then tab, you get to subject, but if you type the name, then want a cc, you press the cc button that is there next to bcc and the empty line becomes writable and cursor on it, then it adds a new empty line below for bcc. Yes, there would be one more line by default in the box, but who cares? ctrl-shift-c or ctrl-alt-c could mean add cc, maybe? The whole thing feel cumbersome to use. Yes, I get it is nice to be able to select a whole email address clicking on it, but I don’t know, the implementation of all of this feels unnatural and should be revised for more seamlessness.

    My folders keep compacting often for a very long time during the day and it prevents me from moving emails around for many seconds. I don’t know how it can find more than 1GB compacted many times during the day. I think it started doing that at the end of version 68, though.

    Sometimes, Thunderbird stops auto-fetching emails and I need to manually get them. If I stop and start the app, it starts to auto-fetch again.

    The whole thing seems a bit less fluid than before. I feel like there are background threads doing I don’t know what in there.

    With Avast, I can’t anymore put an IP address as smtp server name instead of the name. It will say the server doesn’t correspond. Maybe this version 78.3.1 fixes it, but it happened after upgrading even if the smtp server ip address was already there and working on version 68, so not sure that the initial account setup screen will be of any help when you manually go change it in a current account settings post setup.

    I also find the new folders a bit ugly. I like the previous design, but this is a minor annoyance, not an issue. I get that TB should be more friendly to scaling.

    It is extremely annoying that the Lookout extension doesn’t work anymore. Anybody in an office setting will receive the occasional winmail.dat attachment from Outlook servers, so this should not even be an extension for a serious product, it should be built-in and maintained (should not be hard). Same with better caldav integration. It should be easy to set up a phone to synchronize with Gmail contacts and Calendar and Thunderbird all together. That is basic business needs and should be a priority in development so Thunderbird gains more ground in enterprises.

    Thunderbird is such a good product with such a stellar track record of reliability (maybe developing it less helped in the recent years for stability). It is a shame to see such a mature product suffer from regressions like this and it doesn’t seem easy to file bugs or complain and have them fixed quickly.

    I wish the developers would take more care to not break it more when developing, especially when it comes to cosmetic changes for which the value is not clear. We are already busy enough dealing with Windows 10 and its bugs as a service.

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