Betterbird Blog

We've shipped Betterbird 140.13.0esr-bb25 today. Please refer to the Release Notes for full details.

The Thunderbird had quite some trouble while building the release as mentioned in this earlier article. In fact, as they forgot to update the version number, their first successful build, not mentioning about eight failed builds, was built as 140.12.1/build2. Go figure. Three builds later they finally produced a correct build. However, the underlying Gecko version is already at 140.14.0, which could potentially affect some add-ons which are configured to only function to version 140.13.0.

Back to the Betterbird release. This release contains fixes some important bugs:

Zooming of images in links is back, after being removed from version 140.12.0, but this time controlled via preference mail.allow_zooming_image_links.

Spellcheck now works when the desired languages are stored in preference spellchecker.dictionary as a comma-separated list, for example: en-US,de,es-ES.

As mentioned, full details in the Release Notes.

Thunderbird 140.13.0 is due on 21st July 2026, but the Thunderbird folks have trouble building it. So, according to the motto that was coined when Thunderbird was run by volunteers, not 50+ staff turning over 10+ million USD, it will ship when ready.

We depend on a correct Thunderbird build, so Betterbird is also delayed. On the positive note, we managed to ship the next version on the 20th of July 2026.

Today we shipped the first version in the new 153 ESR series, Betterbird 153.0esr-bb6. At the moment, this is only available for Windows, in a few days, we'll offer binaries for for Linux and Mac. We'll see how stable this series turns out to be and when we will start promoting it as the new primary version superseding version 140.

We've analysed available bug fixes for Thunderbird carefully and we're shipping 32 fixes and features that the Thunderbird folks are so far not including in their 153 ESR series.

On top of the 32 extra fixes and features, Betterbird has another 220 improvements. We're happy to report that we just concluded an AI review of all patches and address the minor issues found before this release. Of course the current 140 ESR series will also be updated when 140.13.0 ships in the next few days, whenever the Thunderbird folks are ready.

Like always, everything is documented in the Release Notes.

Today we shipped the last version in this year's beta program, Betterbird 153.0b9-bb5. We only shipped five beta versions, while the Thunderbird folks shipped nine versions, some with little or no relevant content, for example their releases revolving around there Thundermail system add-on which is disabled via a preference in Betterbird.

Next week we will ship Betterbird 153 ESR, first for Windows and in due course for Linux and Mac. We'll see how stable this series turns out to be and when we will start promoting it as the new primary version superseding version 140.

True to our motto

Betterbird is better than Thunderbird in three ways: It contains new features exclusive to Betterbird, it contains bug fixes exclusive to Betterbird and it contains fixes that Thunderbird may ship at a later stage

we are currently shipping 26 27 fixes the Thunderbird release team hasn't included in the 153 series, and which are only available on the Daily (alpha) channel, and months down the track, also on Thunderbird's regression-ridden release channel.

These 26 27 fixes include interesting new functionality, like the ability to store message (.eml) attachments directly in a folder, close to tray, Quick Look preview of attachments on Mac, various functional fixes, and also fixes for five more or less rare crashes.

Update: The Thunderbird folks decided to spin another beta, 153.0 beta 10, just to include one more fix, so Betterbird is now only 26 fixes ahead.

Today we're starting our beta program for Betterbird 153 with 153.0b1-bb1. Please refer to the Release Notes for full details.

We're shipping this only in English and for Windows. Language packs for other languages are available.

Note that we're just starting to gain experience with the new 153 series, so please do not use this version in production yet. Also note that Thunderbird migrated password storage from logins.json to logins.db, so when downgrading, you need to re-enter all your passwords (or restore the previous logins.json file).

We've shipped Betterbird 140.12.0esr-bb24 today. Please refer to the Release Notes for full details.

This release contains fixes some important bugs:

Cancel sending had broken in Thunderbird 135, and no one noticed. We've already written about it. This is fixed in Betterbird 140 now, the Thunderbird folks fixed it for release 153.

Secondary sort is not a well-known feature. To make it a bit more obvious, Betterbird shows secondary sort indicators on column headings in table view where appropriate. Those weren't aligned correctly in default and relaxed densities.

Betterbird had a widely misunderstood feature where the user could zoom images in links if they were oversized. We had a few complaints since people didn't recognise the link, and if they did, had to used the context menu to open it. Finally a user sent us a sample e-mail which was rendered quite incorrectly due to the feature. That was the last nail in the coffin and the feature was dropped.

Lastly this release fixes a few issues with reversed sorting and collapsing a thread to the most recent message. This is driven be preferences mailnews.reversed_threading and mailnews.collapse_thread_to_most_recent. Check this article for details about those function.

Today Thunderbird 153 is entering its alpha stage, also called Daily. We've started to adjust our roughly 250 patches to the new upstream code, with presently 35% done already. (Updates: 27th May 2026: 57% done, 31st May 2026: 87%).

We plan to release a Betterbird 153 beta, also called "future", when Thunderbird 153 beta is released on the 16th June 2026. Betterbird 153.0 ESR will ship around the 21st of July.

We'll see how immediately usable it will be. As a reminder, Thunderbird 102 and 128 initially shipped with backend dataloss issues, 115 had many frontend issues. These series stabilised at around dot release NNN.3.0. Let's hope that 153 will be equally quiet as 140. After all, Thunderbird has been shipping monthly releases from March 2025 (version 136), and despite those being regression-ridden, they have helped to improve the overall quality for the ESR release. Fingers crossed!

We've shipped Betterbird 140.11.0esr-bb23 today. Please refer to the Release Notes for full details.

This release contains some significant improvements.

The story started when a user alerted us to a problem with reversed threading. We fixed that and while doing so, hit a few ancient threading issues described in this bug report. Miraculously, the Thunderbird folks woke up and fixed the issue and a few related ones, so threading is a whole lot better in Betterbird 140.11.0esr-bb23. Additionally, we fulfilled a long-standing wish to be able to collapse a thread to its most recent message and not the original message. This can be enabled with the preference mailnews.collapse_thread_to_most_recent. We dedicated this blog article to the subject.

One of two further issues we fixed by popular demand was better support for internationalized domain names (IDNs), also called Umlaut domains, since in Germany they are used to include äöü in the domain name. In general, that is not recommended, since even in the year 2026 it causes a host of issues. However, with Betterbird, sending mail to such domains works correctly now. Details in this blog article.

Finally we made resetting the folder sort order of subfolders available for all folders containing subfolders, not only server root folders. It's unclear why this restriction exists in Thunderbird.

We've shipped Betterbird 140.10.0esr-bb21 today. Please refer to the Release Notes for full details.

As the new ESR version 153 is already on the horizon being scheduled for the 21st of July 2026, development of the current ESR 140 has somewhat slowed down. The Thunderbird folks are not shipping anything in their 140.10.0 apart from security fixes in the Mozilla platform and more complete localisations.

We're shipping Betterbird for the first time in Portuguese from Portugal. This was made possible be the tireless effort or volunteer Hugo from North-Portugal. Portuguese is tricky, they have a polite verb forms, like German, French, Spanish and many other languages, and they had a orthography reform in 1990, which wasn't widely accepted, so people still use the old spelling. Thunderbird opted for the polite form and adherence to the reform, so we needed to adopt the same, much to the discontent of our translator who argued that the familiar verb forms are more adequate in today's Portugal. He also had to fix the Thunderbird localisation for Portuguese, so Betterbird (and Thunderbird) can now ship a proper localisation without "English patches" here and there. Thank you, Hugo!

By popular demand, we've changed the icon for CardDAV address books to make them more distinguishable:

Lastly, we fixed a long-standing issue with permanently decrypted PGP messages. After Thunderbird removed this feature in version 78, we implemented it in Betterbird 91, and Thunderbird followed in version 102. However, when decrypting a signed and encrypted message, the signature wasn't shown as valid any more. This has now finally been fixed:

Note that from version 115, signed and encrypted messages use a "combined" MIME layer, so when decrypting the signature is lost regardless. Therefor the fix only applies to messages created before version 115 or those which are now created forcing separate MIME layers with preference mail.openpgp.separate_mime_layers.

We've shipped Betterbird 140.9.0esr-bb20 today. Please refer to the Release Notes for full details.

Here are three important new features and changes:

We improved the "delayed sending" capability by making sure that a message which is scheduled for sending is in fact not sent once it's opened for further edits with "edit as new message".

Betterbird/Thunderbird allows to convert an e-mail message to a calendar event or task. The original message is linked to the event/task. However, that link wasn't reliably displayed. That was fixed and we added a button Open in Folder (see screenshot) that allows to go back to the original message.

Lastly, localised versions, like the German version, no longer include the standard Mozilla English US dictionary. We had users who expressed that they wanted to remove the dictionary, which wasn't possible. Also, it allows more flexibility in choosing an English dictionary. Here are some choices:

• The stock-standard Mozilla dictionary, which is rather basic.
• The English US dictionary maintained by Marco Pinto.
• The British English dictionary maintained by Marco Pinto which is the better choice for European use.