Betterbird Blog

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.

We've shipped Betterbird 140.6.0esr-bb15 today. Please refer to the Release Notes for full details.

Update 8th December 2025: We had to replace the entire release with "build2" since advancing the Thunderbird "fix" for an IMAP bug introduced random crashes. On closer inspection, that code change is likely to have undesired effects, including crashes.

We've addressed issues reported by users in the last four weeks and implemented some new features.

First and foremost, to fund the project, when launching this version for the first time, it will open the end-of-year donation drive page in your browser. Unlike Thunderbird, which is constantly nagging, we're asking for donations this way only once a year in December.

A user who is migrating from Postbox motivated some improvements to the search functionality, see this post for details.

Some of the fixed bugs that were related to searching, for example we rectified and issue that prevented encrypted S/MIME messages to be indexed; a feature introduced in Betterbird 115.

Miscellaneous fixes include missing localisations, where the program talked about Thunderbird instead of Betterbird, and a fix for the much-dreaded "phantom menus" mentioned here. Users of "attachments on top" in the compose window can now reduce the height of the addressing header when many files are attached.

We've shipped Betterbird 140.5.0esr-bb14 today. Please refer to the Release Notes for full details.

We've addressed issues reported by users in the last four weeks.

The Betterbird-native new mail alert on wrong monitor issue is finally fixed, and preference mail.notification.show_on_app_screen should also be working now. We revived preference mail.folderpane.sumSubfolders which had become a victim of Supernova-Kaboom in Thunderbird 115.

Users of the Proton Mail Bridge can now unsubscribe from the likely unwanted so-called "no-select" folders Labels and Folders after setting preference mail.imap.allow_unsubscribe_noselect.

The pesky calendar scroll issue when switching tabs was also fixed by advancing a Mozilla patch. We're also advancing eight bug fixes which are not shipping in Thunderbird 140 ESR yet. As far as providing recent bug fixes to ESR users is concerned, Betterbird is about 50 fixes ahead of Thunderbird.

Finally, the "Recent Destinations" menu was returned to its original state of only showing folders to which messages had been recently moved, the sort order is now based on latest use.

We've shipped Betterbird 140.4.0esr-bb13 today. Please refer to the Release Notes for the full details.

Once again, we've addressed issues reported by users in the last two weeks.

One user wrote to us that they wanted to get more information about the path of a folder, so we added a tooltip to the message list header. The Thunderbird folks jumped onto the bandwagon, dusted off an ancient bug from 2007, and added a tooltip in the folder pane as well. But of course the improvement is already available for Betterbird users while at Thunderbird, they're still thinking about it.

One request about suppressing an unnecessary prompt when opening a link in the compose window came is so late, that half the release had already left the station. So apologies to the Mac users who will have to wait for the next release. But then, most users might not know the feature in the first place or are not too bothered to answer the additional prompt.

Of course the Betterbird-native new mail alert on wrong monitor issue, which had crept into the previous release, was fixed as well. UPDATE: That was wishful thinking, yet again, we had to prepare a "latest build" one day after the release to really fix it. Here it is in English and German.

Detaching an attachment didn't work since the beginning of the 140 series months ago, and only one user noticed?

Finally, it's worth mentioning that when saving a message using its subject as file name, the same file name sanitation is now applied on all platforms. Trigger was a user report that Windows volumes mounted on Linux need the Windows rules applied, not the Linux rules.

After the preparations described in an earlier post, we've shipped Betterbird 140.3.1esr-bb12 today. Please refer to the Release Notes for the full details.

This release contains a lot of fixes for issues raised by our users in the last two weeks. The upstream Thunderbird release 140.3.1 also contains more fixes than usual. Six of those fixes had already shipped in Betterbird earlier.

Update a few hours later: There is no release without some sort of issue. We just got a report that native new mail alerts, so not system alerts, are displayed at the right corner of the right monitor in a dual-monitor when before they are displayed at the right corner of the left monitor.

Here's what happened: As stated in the Release Notes, we tried to mitigate random flashing of Betterbird-native new mail alert in top left corner of the screen. So after creating the window, we now move it "off-screen", but it may end up on a monitor to the right and finally at its corner. A picture says more than 1000 words: Some users may work around the issue by setting the preference mail.notification.show_on_app_screen. If you're affected, please let us know and we'll provide a solution.

Or you can try the latest build for Windows in English. Yes, how ironic, a "latest build" on the day of the release.