Betterbird: Release Notes

Betterbird 153 offers all the features and bug fixes mentioned in the feature table on the home page: Multi-line view, full account colours, attachments on top, complex search terms, regular expression search, search in encrypted messages, improved Windows and Linux system tray integration, and many more. This page contains features added during the 153 series. Check the release notes of the prior series for features that got added before the 153 series: 140 series, 128 series, 115 series, 102 series, 91 series.

This version is not offered as an update. Changes will ship in the next release.

Fixed in this version:

FIXED - Regression: Activity Indicator in Unified Toolbar and progress bar in status bar for downloading messages, compacting, etc. not working
FIXED - Linux: Wayland content offset ("phantom shadow") after window is restored after being "minimised to tray" - GitHub #399
EXPERIMENTAL FIX - Windows: Sporadic empty new mail alert on Windows when Betterbird-native XUL alert is used - GitHub #599
EXPERIMENTAL FIX - Linux Flatpak: Interoperability with KeepassXC - GitHub Flatpak #340
FIXED - "Phantom messages" (Unread, dated 1967/1970, empty details) when archiving in threaded unified folder

Various minor fixes that Thunderbird isn't shipping yet in the 153 series:

Bug 548507 Bug 1923075 Bug 2056491 Bug 2067593 Bug 2069089 Bug 2073409 Bug 2075909 Bug 2076034 Bug 2076335 Bug 2076569 Bug 2076654 Bug 2076665 Bug 2076742 Bug 2076749 Bug 2077839

Based on Thunderbird 153.4.0esr, release notes.

Note that Betterbird 153.4.0esr-bb10 is based on Thunderbird's release candidate "build1", which was the only release candidate available on the delivery due date, 29 September 2026. The Thunderbird folks have missed that deadline and are still preparing more release candidates. Therefore, some changes which may be included in Thunderbird 153.4.0, when it finally ships, are not included in Betterbird.

Fixed in this version:

NEW - Linux: System Tray icon now offers a context menu to quit Betterbird. This matches the Windows functionality.
FIXED - Incorrect console errors (Missing resource in locale XX: devtools/client/toolbox.ftl) when language packs are used - Bug 1904591
FIXED - Gloda constraint errors, logged in the Error Console - Bug 2060072
FIXED - Unneeded account colour indicator in Account column in table view if the account didn't have a colour
FIXED - Various issues with Tags folder view mode - GitHub #581 GitHub #603 Bug 1954441
FIXED - Lost line breaks in plaintext composition under certain circumstances - Bug 2074786
FIXED - Status bar information "Searching..." not cleared when Quick Filter search was complete

Fixed in version 153.3.0:

CHANGED - Linux: Restore the main window to its previous position after the next start
CHANGED - Linux: hyprland and x-cinnamon now in the list of supported desktop environments for "minimise to tray"
FIXED - Linux: Maximised windows weren't restored correctly after "minimise to tray" - GitHub #594
FIXED - Linux: CPU load of 10-15% on X11 systems when Betterbird was minimised to the tray, ie. main window invisible (caused by deficiency in Mozilla platform) GitHub #563
FIXED - Windows: Clicking on a Windows system notification, like "Mark as read", brought the main window to the foreground
FIXED - Windows: Windows system notifications contained the string "undefined" instead of the correct folder name
FIXED - In the recent folder popup, when using "Most Recent + Alphabetical", the alphabetical part wasn't sorted
FIXED - Window control buttons (minimise, maximise, close) missing when menu bar and windows system title bar were hidden
FIXED - Retry and save to local folder not working after move to local Sent folder failed - Bug 2068501
FIXED - Constant error notifications when working on offline profile with POP accounts - Bug 2071585

Fixed in version 153.2.0:

CHANGED - Linux: When the application is minimised to the system tray, a new application launch will restore the last window, not all minimised windows. This matches the behaviour on Windows. - GitHub #590
FIXED - Linux: System tray didn't work under Mate. Now the preference mail.systemTrayNoSniSupport list desktops which don't have SNI support. In this case a legacy fallback is used. (This can be used for for Cinnamon when no XApp Status applet is installed.)
FIXED - Linux: System Integration dialogue launched multiple times. Launcher's full path in the GNOME Shell Service was incorrect, handler for the net.thunderbird scheme wasn't listed in .desktop file - GitHub #591
FIXED - Template and archive folder location confusion. "Reply with Template" sometimes missing in Filter Editor. - Bug 2066371
FIXED - Quick Filter: "Match Address Book" checkbox not working (inverted result) - GitHub #592
FIXED - Showing Gloda results as list immediately didn't work. Switched to official Thunderbird solution which uses preference gloda.show_as_list_by_default - GitHub #589
FIXED - Signature missing below the forwarded block in plaintext forward - Bug 2063939

Fixed in version 153.1.0:

CHANGED - The underlying library for Linux system tray support was upgraded from libayatana-appindicator (Sept. 2023, commit 9201035) to the new libayatana-appindicator-glib (June 2026, version 2.0.3). This may cause changes to the extablished functionality. Please get in touch if you notice any problems.
FIXED - Error when dragging inserted image in compose window - Bug 2061788
FIXED - New messages sometimes had their "new indicator" (star) cleared prematurely - Bug 2063838

Fixed in version 153.0:

NEW - Support for "close to tray" while maintaining "minimise to tray", see this blog article for details
CHANGED - Images in links are again zoomable controlled by preference mail.allow_zooming_image_links
CHANGED - Integration with Thundermail disabled, see this blog article for details. This includes removing the application menu entry.
FIXED - Placing native notifications onto the application screen with preference mail.notification.show_on_app_screen not reliable
FIXED - Spellcheck in calendar descriptions. This now follows the inline spellcheck preference mail.spellcheck.inline and the dictionaries selected via preference spellchecker.dictionary (comma-separeated list) - Bug 1754162
FIXED - Missing space between HTML signature and quote when replying "on top" - Bug 2005898
FIXED - Calendar item description was black on black in dark mode if preference mail.dark-reader-compose.enabled was set to false
FIXED - Search in body of messages with encoding quoted-printable didn't work when message ended with a soft linebreak (=) - Bug 2054385
FIXED - 15 minor issues after an AI review of the entire Betterbird patch set of about 220 patches. Most visible was the erroneous hiding of the "All Tabs" button on overflow of the horizontal tabs bar.
FIXED - Error in feed menu
FIXED - Problems when "show most recent child in collapsed thread root" was used: Newly arrived messages didn't get threaded properly when the thread was collapsed

Various minor fixes that Thunderbird isn't shipping yet in the 153 ESR series:

Bug 11013 Bug 187997 Bug 204612 Bug 450059 Bug 474719 Bug 520437 Bug 534602 Bug 624082 Bug 647046 Bug 709449 Bug 770888 Bug 1121151 Bug 1616753 Bug 1675937 Bug 1698140 Bug 1713625 Bug 1781792 Bug 1787958 Bug 1876127 Bug 1883816 Bug 1891713 Bug 1907729 Bug 1917314 Bug 1921163 Bug 1939379 Bug 1949640 Bug 1991785 Bug 2000913 Bug 2007074 Bug 2007529 Bug 2016999 Bug 2029781 Bug 2038199 Bug 2041038 Bug 2044587 Bug 2045506 Bug 2047459 Bug 2047704 Bug 2047887 Bug 2047970 Bug 2049110 Bug 2049537 Bug 2051122 Bug 2051561 Bug 2051567 Bug 2052714 Bug 2052807 Bug 2052827 Bug 2053691 Bug 2054385 Bug 2054465 Bug 2054872 Bug 2055585 Bug 2056063 Bug 2056286 Bug 2057048 Bug 2057187 Bug 2057195 Bug 2057710 Bug 2058447 Bug 2059469 Bug 2059950 Bug 2060181 Bug 2060192 Bug 2060763 Bug 2061085 Bug 2061610 Bug 2061642 Bug 2062054 Bug 2062951 Bug 2063333 Bug 2064462 Bug 2064660 Bug 2065097 Bug 2065806 Bug 2066883 Bug 2068200 Bug 2068867 Bug 2069710 Bug 2070351 Bug 2074333 Bug 2075316 Bug 2075594

Note that Mozilla and therefore Thunderbird and Betterbird changed the encryption of user names and passwords in logins.json between versions 140 and 153. When downgrading, you need to re-enter all your passwords (or restore the previous logins.json file from logins-backup.json).