Betterbird Blog

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.

We've shipped Betterbird 140.8.0esr-bb19 today. Please refer to the Release Notes for full details.

This new release offers four new functions and a fix for an annoying issue. Here are some details:

The add-on Send Later to schedule sending of messages has many users. Its author doesn't test his add-on in Betterbird, instead he publishes this disclaimer (quote):

Send Later is known to have issues with Betterbird
The Send Later add-on is not regularly tested with the Thunderbird fork called Betterbird, and there are known, unresolved issues which may prevent the add-on from functioning as intended. Using Send Later with Betterbird is therefore not recommended.

We're not aware of any issues, other than the ~55 issues the add-on has anyway. But the good news is, delayed sending in the background is now supported in Betterbird, if you set the following two preferences:

mailnews.sendInBackground set to true and mailnews.sendInBackground.DelayMinutes set to the desired delay in minutes. Be aware that if you close Betterbird before all messages are sent, there is currently no warning.

This is not aimed at replacing the add-on completely, it's aimed at providing a "send delay" that users of MS Outlook are used to.

As we detailed in previous posts like this one, we're now signing our Windows binaries with a code-signing certificate from a reputable source.

By popular demand, the 'Search PreferredSearchEngine for "..." ' option is now also available in the context menu in the compose window.

People who have used Thunderbird for a long time will know that for IMAP accounts, messages read on the server with a different client, like a mobile device, were not subjected to message filtering. That was later changed by introducing preference mail.imap.filter_on_new. However, the filter didn't work when it was run after the junk classification. This has now been fixed.

We've shipped Betterbird 140.7.1esr-bb18 today. Please refer to the Release Notes for full details.

The Thunderbird folks are preparing their 140.7.1 release for next Tuesday, 27th January 2026 to fix a vulnerability in an OpenPGP edge case. Due to scheduling constraints, we're already shipping this now.

Since only 13 days have passed since our Release 140.7.0esr-bb17, this release only contains a few items. By popular demand, we're now distinguishing in the Activity Manager now whether messages were downloaded or not by giving the icon a different colour:

We've also advanced 11 bug fixes the Thunderbird folks are not shipping to their ESR users, refer to our opinion about this policy in this prior blog post.

We've shipped Betterbird 140.7.0esr-bb17 today. Please refer to the Release Notes for full details.

Since only 11 days have passed since our Release 140.6.0esr-bb16, this release only contains a few items. By popular demand we implemented a "reveal" button in the primary password and mail password prompts.

We decided to start the New Year with a fresh release of Betterbird 140.6.0esr-bb16. Too many fixes had accumulated since shipping "bb15" at the beginning of December:

• A user alerted us to a defective French localisation. The issue is also present in Thunderbird 140. We made a "spot fix" to include the missing strings.
• A user had asked us to provide a "dark reader" switch for the compose window to work around "back on black" issues.
• By popular demand we've implemented an option to include the event description in the mail body of the scheduling message.
• We're now enabling address book categories for compliant CardDAV servers which support vCard v4.0.
• "Recent Destination" now include a short MRU list on top of the longer alphabetically sorted list.
• By popular demand, filenames can now contain commas with -compose "attachment=..." is used.
• There was a Mozilla editor issue where the "insertion point" (caret) was displayed incorrectly. We're advancing Mozilla's fix since the issue was rather annoying.
• And finally: Embedded SVG images weren't displayed correctly under some circumstances, another puzzling issue.

And there is more, so please refer to the Release Notes for full details.

Update: No release without an issue. This time the localised strings for the new Categories functionality were missing, so all localised versions and language packs had to be replaced. This happened at 20:00 GMT.