Betterbird Blog

Import of data from the local PST files of a Microsoft Outlook profile was not working well in Thunderbird before 2011, when famous Russian developer Mike Kaganski^*) re-implemented it in bug 207156. His work was committed here with this changeset. That was in 2011 in Thunderbird 6. Back then, our project leader was working with Mike, mostly doing testing. Mike did a few more tweaks, for example here and here, so the feature was stable that year in Thunderbird 11.

With the advent of JS Mime, a new implementation of MIME processing written in JavaScript, Outlook import broke again in Thunderbird 38 due to threading issues. The fix was made in this bug ready for Thunderbird 60 by our project leader.

(The text below has been corrected on 8th November 2025, the initial information was incorrect.)

It's been working since then, but the advent of Outlook 2013/2016/2019, Office 365 and the modern Outlook app have changed the situation. Here is what is still working to this very day:

To import a PST with Outlook 2013/2016/2019 or Outlook 365 installed, add it to an IMAP profile (with OST file) as an additional data file.

This screenshot was taken after a successful import from Outlook 2010: It is possible that modern versions of Betterbird/Thunderbird have additional bugs, so if there is an issue, we recommend using an older version, for example Thunderbird 12 (we didn't test it). Older versions also give a more informative summary panel that the new kids on the block who took over Thunderbird axed in version 128 (bug 1851608):

If you're using Outlook 2013/2016/2019 or Outlook 365 on a POP account or the modern app, you will see this:

*) Mike is famous for cracking bug 393302, the dreaded MAPI x64 bug, that no one had been able to solve and that prevented Thunderbird from shipping 64-bit binaries. That was back in 2019, and the fix was backported to Thunderbird 60.

Have you ever wondered why Betterbird follows the Thunderbird ESR (Extended Support Release) channel and not the Thunderbird Release channel? The answer is easy: The Release version is riddled with regressions that slipped through the beta phase. Even Thunderbird users seem to be aware of that, as according to the latest published statistics, and despite the best effort of the Thunderbird folks to push their Release channel to users, 73% are still on ESR. They prefer stability to fresh regressions and partly implemented and non-functional new features.

Three examples from the current version 144. This is shipping with the new reworked so-called Account Hub, which is very buggy, this bug only has 22 duplicates. Next, 144.0 shipped on 14th October 2025 with a bug, causing the taskbar button of the compose window to disappear from the taskbar. This was quickly fixed with a new release 144.0.1 two days later. Last not least localisation of IMAP folders for drafts, templates, sent messages, etc. is broken. Users of localised versions see the English names.

One argument for the Release channel has been, that new features would reach users faster. While this is true in theory, the practice is different. For example, the much-touted Microsoft Exchange integration via EWS is still not feature-complete in the current release. Users are left to find out in which way their the Exchange account behaves like normal local or IMAP accounts, and which features still need to be implemented.

In Germany there is a term for this: "Bananaware", the product ripens on customers' systems.

We had a few reports from the United States and Australia regarding slow download speeds for our larger binary files (.exe, .zip, .tar.xz and .dmg). Currently all files are hosted at our hosting provider in Germany, so "overseas" users are suffering from transatlantic (or transpacific) latency and limited peering bandwidth.

Therefore we made downloads also available via the Bunny Content Distribution Network. In Firefox, it looks like this:

This is a paid service, so the project has to finance every download. If our total download volume of currently 3.5 TB per month ran via this service, we would incur a considerable cost.

Therefore using CDN is a click away from the regular download page at www.betterbird.eu/downloads/, and we ask our users to use the service with care. We assume that no European user would need it. If the costs run too high, we will have to restrict this to certain regions.

Do you know which folders are shown in Thunderbird's "Recent" folder list? Well, in the context menu in version 140 that's been renamed to "Recent Destinations", so that could be a hint. The change was made in this bug.

This list appears in the context menu, but also in the Filter Rules Editor. Yes, the list contains folders into which messages have been moved recently, but only manually, not by filter. This is implemented via a folder property MRMTime, where MRM stands for "Most Recently Moved to Manually".

One user asked us why folders that were recently "used" or opened weren't in the "Recent" list, as it would make things a lot easier when defining new filters. We thought that was a valid arguments, and given that the "Quick Folder Move" add-on has used MRU for ages, we changed the behaviour in BB 140.3.1 to make the "Recent" list hold the most recently used folders.

But every change breaks someone's workflow. The first report we had was from someone who used the "Recent" list to move misclassified SPAM back to the Inbox. They only wanted to see their familiar move targets. The next report came from someone who really only wanted to see recent manual move destinations, instead of a very busy list that now records lots of folders.

To that add the fact that some don't think that the alphabetic order in that list is great, so they filed this bug.

BTW, the Thunderbird folks also considered making that change, but dropped the idea stating: ... by selecting a folder, it becomes "used". That means the "recent" context menu for a message entry will always include at least one entry (the current folder), and every folder being opened will be added. Since we have a limit of 25 folders in that menu, the folders used for actually moving or copying messages might no longer be listed.

FINAL VERDICT: We reverted the change but we're still using MRU folders in the Filter Editor. Try it here in English and German.

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.

In this post we talked about the mishaps which have been common when preparing Thunderbird ESR releases, and version 140.4.0 ESR is no different. Not PhotoShop'ed, you can see it here. The red B's mean that the build failed. Sure, the Thunderbird folks will have another go to get it going, but this is this is already the second attempt, here is the first.

UPDATE: After fixing what is called "build bustage", they got the release built, but they made three mistakes, here listed in declining order of severity:

1. They are not using the correct changeset of the Mozilla base software. For version 140, Mozilla did another "build 2" to plug a security vulnerability.
2. One patch was backported incorrectly.
3. Finally, they pushed all the patches separately, hence increasing the server usage and CO₂ footprint.

But who cares about correctness as long as the donation money is flowing in.

On 1st October 2025 we stopped accepting USD donations via PayPal. Here's why. To begin with, PayPal changes a whopping 4.89% (base 2.90% + 1.99% US surcharge) + 0.30 USD fixed fee. As an example: On 50 USD they change 2.75%, so effectively 5.5%. And that's not where it stops. With a PayPal account in Europe we are forced to convert USD to Euros at PayPal's atrocious conversion rates. That's were they pocket another 3% of markup. So effectively, for USD donations, PayPal help themselves to 8.5% of the incoming funds.

A while ago we researched ways of transferring the USD to an account or debit card denominated in USD. For starters, our European PayPal account does't allow linking to a USD denominated bank account, they only allow you to link Euro accounts from European banks.

When trying to "push" funds into a VISA debit card, PayPay stops such transfers with dubious error messages, like you can see in the picture: "We're sorry but we were unable to approve your request to transfer $XXXX.00 USD to your card". During the transaction, we see this: And we're not the only ones. The message varies, see this Reddit post:
"There's a problem. Right now, we are not able to complete this transaction" (from Feb. 2024)
"These can't be used for Instant Transfers: Revolut Bank UAB" (July 2024)
but the facts are the same: PayPal wants to enforce their additional fee.

UPDATE: We talked to three PayPal customer fooling agents, and these were their statements:

• Number 1: We at PayPal did everything correctly, the credit card company declined the deposit.
• Number 2: Change the account's main currency to USD and wait two hours, I will call you back. They never did, and their suggestion didn't work.
• Number 3: We received a lecture that the currency in Spain was the Euro and that it was therefore simply not possible to transfer anything out except in Euros.

So two ignorants and one outright condescending.

UPDATE 2A: We filed a complaint and this was there answer:

I see you have tried to complete a fast withdrawal to your card X-xxxx several times but have been unsuccessful. However, this is not due to your PayPal account having some kind of restriction or block for this process. [...] The reason for this error could be that, since it is a fast withdrawal, in which we need an immediate response from your bank, due to not receiving a prompt response from their system, the process fails, and it cannot be completed. This is something rather common with cards issued by international online banks [...].

Then they went on to suggest converting the USD to Euros at 3% commission and transferring them out via the bank account option.

UPDATE 2B: Yet another PayPal answer saying the same thing:

Keep in mind, this does not mean there is something wrong with your card, it's simply that the system determines automatically whether a card can receive a transfer from our accounts or not, if you do not see it listed, or you see an error when trying to select the card for the withdrawal, it is due to it not being compatible with that process in PayPal. In this case, I'd recommend you use your bank account linked to PayPal so you can transfer this balance.

UPDATE 3: Answer from the so-called "international online bank":

Although PayPal allows sending money to Debit or Credit cards, [the bank] only accepts transfers [using] account details, not to the card’s 16-digit number.

So we don't have 100% certainty, but it looks like PayPal did the "right thing", however, it conveniently for them didn't match with the receiving system. Still, it doesn't excuse the mind-blowing (quoted from the Reddit post) exchange rate they apply and the fact that they only allow linking Euro accounts.

UPDATE 4: We tried to link three more different credit cards, but those were rejected right away, two of them seen here:

We're in the process of closing PayPal altogether and setting up Revolut instead.

Note: Screenshot of a genuine PayPal e-mail (logo cropped/blurred for trademark reasons)

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.

Today we're presenting fourteen features that don't exist in Thunderbird, although requests date back to 1999.

Main window:

• Like in every regular application, the menu bar is at the top of the main window. It's surprising that Thunderbird broke that rule in Supernova-Kaboom and users are now struggling with userChrome.css to get it back where it belongs.
• Equally, Supernova-Kaboom got rid of the message counts in the status bar, a UI element which had existed for more than 20 years.
• Betterbird's Windows and Linux system tray icon offer a tooltip, so you can see at a glance in which folders to find new messages.

Improvements for people who like it tidy:

• Some people want Betterbird always start on the same folder, most likely an inbox or unified inbox, no matter which folder was open when they closed the application. That's why Betterbird offers a startup folder.
• Some people open many messages in tab, but they don't want to see those messages again after a restart. That's why Betterbird offers optional tab restore.
• For people with very wide screens there are vertical tabs.
• People with many accounts appreciate Betterbird's implementation of account colours. The old add-on doesn't work any more, and Thunderbird's own implementation leaves much to be desired.

Message list, aka thread pane:

• Long before Thunderbird introduced its space-wasting cards view, Betterbird offered a multi-line view like in Outlook. Individual columns are still present, only the message subject has moved to the second line.
• Many users don't know that there is a secondary sort, that is, you can sort by one column and then by another. That why we're showing secondary sort indicators.
• Ever selected more than one message or a collapsed thread (multi-select) and wondered about the not-so-useful summary view? It can be turned off in Betterbird, so the message shown is the last selected message.

Threading improvements:

• People who use a threaded view appreciate Betterbird's connecting lines that had been used for two decades before they became another Supernova-Kaboom casualty.
• Betterbird also offers reversed threading, so when sort be date descending (newest message on top), the threads are also sorted that way.

Finally, rethreading and message editing:

• Rethreading: In a threaded view, messages can be moved to a different thread, or removed from a thread. In folders containing feed articles, these can also be grouped into threads.
• The subject and other message headers can be edited. This functionality is available via add-ons, but it's better to have it in the toolbox.

The Thunderbird folks are somewhat unpredictable. For 140.3.0 they made their build on a Thursday to be release on Tuesday the following week. Today is Saturday, and they haven't done 140.3.1 yet which is due on Tuesday. Well, "due" is in the eye of the beholder, looks like the old "volunteer spirit" before 2020 with the motto "Ship when ready" is still alive, even with ~50 paid staff and a multi-million dollar turnover. Likely they'll do it on Monday in a hurry. They're already earmarked 12 bugs for backport to ESR 140, but the backport hasn't happened yet.

Meanwhile we've added more fixes to Betterbird, which will ship in 140.3.1, and which are already available in the "latest build" versions for users who want to try them out early. As always, the Release Notes have the full detail. Amongst the goodies, we're fixing a couple of regressions: disappearing linebreaks when editing mailcites, and OWL default accounts losing their default status. We're also brushing off a fix to the "Junk" button whose context sensitivity was lost in the 2023 Supernova-Kaboom. The Thunderbird folks walked away from a 95% complete solution in February 2025.