Betterbird Blog

Users of reversed threading have always requested to show the most recent message in the thread as the collapsed root, see for example this GitHub report. This has now been implemented.

Note that the most recent message in a thread isn't necessarily the last displayed message in this thread:

The preference to switch on reversed threading is mailnews.reversed_threading. A preview release (lastes build 6) is available for Windows and Linux.

This will ship in the next release. Please let us know your thoughts.

Fixed in build 6: When the view starts with all threads collapsed, the most recent message wasn't shown in the root.

It has been brought to our attention via this Reddit post that the author of Quicktext is blocking use in Betterbird in the future via this commit. The add-on code now checks explicitly for use of the add-on in Thunderbird. This will become effective from add-on version 6.7.

We'll leave it to the assessment of the reader, whether this was done in the best spirit of collaboration in the open source world.

The mentioned Reddit article suggests the use of Clippings for Thunderbird. We tried it, it works.

We know that Quicktext is heavily integrated into some people's workflow, so unless the add-on author drops his stance, we will consider forking the add-on just to adjust the unnecessary checks for Betterbird. That new version would need to be published with a different add-on ID, so it doesn't automatically update to new versions of the original. We would also have to remove the donation facility to the original author and will likely make the forked^*) add-on only available to supporters of Betterbird.

John, please reconsider your position! Have you forgotten your comment, when our ThunderHTMLedit add-on wasn't 100% compatible with Thunderbird for a short period due to technical reasons:

From this day on, the add-on ecosystem for Thunderbird and Betterbird is not the same anymore. There are now cases were add-ons work in Betterbird, but not in Thunderbird. That was not our choice. [...] But it is unlikely that the [ThunderHTMLedit] author is going to release an update, since he does not support Thunderbird anymore.

Of course we fixed the add-on for both Betterbird and Thunderbird. Now, who's going ahead and making his add-on deliberately incompatible?

Update 1: Open source collaboration continues (NOT!) by preventing us from forking the add-on: We were also banned from filing issues or adding comments the the Quicktext GitHub repository.

Update 2: We've now published the latest Quicktext version (which has a bug in the menu on the compose window) here on our website.

Update 3: The Quicktext author reverted the change that made his add-on incompatible. This is available on GitHub as 6.7.2.

Thunderbird still hasn't implemented proper support for internationalized domain names (IDNs) as these two bugs show: Bug 235312 from 2004, Bug 923043 from 2013.

In brief, sending messages to mail addresses at internationalized domains may fail, depending on whether the final server supports so-called SMTPUTF8 (RFC 6531). If it doesn't, it likely also doesn't support UTF-8 headers (RFC 6532), and delivery will fail due to raw UTF-8 in addressing headers. This especially applies to domains hosted at IONOS.

Mail clients like Microsoft Outlook and FairEmail handle the situation somewhat better, since they unconditionally force internationalized addressing headers to ASCII-Compatible Encoding (ACE), which uses Punycode as encoding.

Betterbird has now introduced the preference mail.strictly_ace (similar to mail.strictly_mime which avoids 8bit characters in mail bodies). With this preference set, Betterbird will behave like the two mentioned mail clients and force addressing headers to ACE.

Further reading:

• IDNs
• Punycode

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.

Thunderbird has always been underperforming when measured against its own roadmaps. Now it looks like the roadmaps have been replaced by a list of what the project is working on anyway.

Let's compare the past and current roadmaps. We're focusing on the major items which have accompanied us over the last five years, of which at time of writing (April 2026) none are complete and only one, Exchange support, has a realistic chance of being completed.

Items marked with an asterisk for 2026 (Fluent, Exhange) may be complete for the summer release of Thunderbird 153, the global database will not be shipping in this release.

Important items, like replacing the buggy 26-year-old MIME library of finally providing a decent and contemporary mail editor, are not even on the roadmap.

It's no surprise that things are not progressing with the Thunderbird desktop development, since despite close to 60 staff (of whom 15 are managers, CEO, COO or directors), the project has "diversified" into Thunderbird for Android (rebadged K-9 app), Thunderbird for iOS and so-called "Services" where the project actually supplies mail accounts. A developer recently wrote that the desktop team was small; going by the mentioned page and not counting director/manager and release engineer, there are only 12 people.

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.

If you read the article about discontinuing the Revolut payment link, you will already have heard of credit card testing attacks: Fraudsters effect (small) payments to "merchants" to test the validity of stolen/leaked credit card details. As you can see in the picture, nine attempts were made within less than 40 minutes. All Revolut did was to block our account, they don't offer any mitigation tools.

As of March 2026 our Stripe payment USD link also came under attack. It started with small payments between $0.50 and $2, which we blocked, but later they increased to $5 to $20, and even payments of $100 or $1000 were "tested".

To mitigate the issue the following measures were taken on top of Stripe's so-called Radar which has its own heuristic for fraud detection:

• Small donations blocked
• Donations from Algeria blocked, there seems to be a nest of fraudsters
• Now requiring 3D Secure payments (when available)
• Stricter address checking
• USD payment replaced twice and all payment links now obfuscated (supplied via JS on page load or user click)
• Proactive refund of suspicious payments, since every dispute carries a fee of $20
• Last not least: The Link payment method was disabled, a Stripe invention, which makes these attacks faster for the fraudsters.

Unfortunately, Stripe's own mitigation isn't very good, in on case there were at least 8 failed tests from the same IP address within 33 minutes, and Stripe still allowed a subsequent payment from that IP address, which of course we refunded immediately to avoid a costly dispute:

On this topic, Stripe support made the following statement: Stripe is first and foremost a payments processor. We facilitate your interaction with the card networks and issuers, and we provide a PCI compliant way to do so. Payment processing is not the same as dedicated fraud protection. We do have safeguards against fraud, and we do try to weed out risky transactions without blocking legitimate charges - it's a pretty delicate balance. There's simply no algorithm that can replace the role of the merchant's manual review of orders. But even these powerful, dedicated solutions are not foolproof; the strongest, and best, line of defense is still manual review.

If your genuine donation in USD was declined, please get in touch and we'll find a different payment option. In a dialogue with a donor we found out that Bank of America generally allows outgoing ACH payments. For "regular" customers they charge a fee, it's free for customers with a "preferred status".

Strange what tasks arise in an open source project which aims at providing the world's best e-mail client.

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.

Thunderbird released version 140.7.2 yesterday to follow Firefox 140.7.1 which fixes a security issue, a heap buffer overflow in libvpx. That's a video codec. The Thunderbird folks wrote this in their advisory:

In general, these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser or browser-like contexts.

So, only Betterbird users who use Betterbird as a web browser, or browsing news feeds with embedded videos may be affected. Since the security risk is extremely low and since Betterbird 140.8.0esr-bb19 will ship before the 24th of February 2026, we decided to skip this release.

The "colourful" picture shows the all the test failures that occurred in Thunderbird's release automation and are shown in the so-called "treeherder" (dashboard). Each orange box is a test failure, and it's not advisable to ship the product with so many test failures without investigating them.

In other words: Even if we had built Betterbird based on this Thunberbird release, it could be quite broken. BTW, this is not the first release chagrin, refer to these earlier articles [1] and [2] for more.

Update: Apologies to the Thunderbird folks for the incorrect statement above. We heard that the test failures were analysed and that they came to the conclusion that despite what was displayed on the dashboard, the product showed no functional failures and was safe to ship. That was confirmed by their QA team, in fact, we also tested that Thunderbird release and didn't see failures.

Our article was overreacting to the fact that in the past, test failures were ignored and the product did get shipped with minor functional issues.

Finally no encoding issues with the re-issued certificate. See our previous post for details.