Thunderbird Desktop
Version 144.0beta | Released September 17, 2025
Check out the notes below for this version of Thunderbird. As always, you’re encouraged to tell us what you think, ask for help, or file a bug in Bugzilla.
These notes apply to Thunderbird version 144 beta 4 released October 6, 2025.
System Requirements: Details
- Windows: Windows 10 or later
- Mac: macOS 10.15 or later
- Linux: GTK+ 3.14 or higher
What’s New
new
Enable support for Microsoft Exchange via Exchange Web Services
What’s Changed
changed
Flatpak runtime has been updated to Freedesktop SDK 24.08
What’s Fixed
fixed
Copying text from some error alerts was not possible
fixed
Fastmail CalDAV app password access failed due to forced OAuth regression
fixed
Newly created folder was missing under "Recent" when moving a message
fixed
Sorting by threads only brought threads with unread top messages to the top
fixed
News message marked read after NNTP error prevented retrieval from server
fixed
Inbox 'Location' column was not translated in French locale installation
fixed
Not all headers were signed when creating digitally signed OpenPGP email
fixed
Changing identity in compose window caused modified draft not to be saved
fixed
Shift-click 'Compose Message To' on 'mailto' link did not open in plain text
fixed
'Copy Message to' action in a newsgroup filter did not work
fixed
Thunderbird could not import profile located at the top level of zip file
fixed
Thunderbird did not clearly fail when importing profile from a bad source
fixed
No way to distinguish between Thunderbird Release/ESR in Windows registry
fixed
Multi-attachment delete/detach confirmation only cited first attachment
fixed
Thunderbird hung when auto-checking multiple accounts for new messages
fixed
Sending emails via servers with self-signed certificate did not work
fixed
Could not copy an event in multiweek or month view by drag-and-drop
fixed
Calendar discovery with certificate error displayed multiple exceptions
fixed
Visual and UX improvements
Fixed in beta 2
What’s Fixed
fixed
Delete key failed to prevent deleting attachments in OpenPGP messages
fixed
Sender avatar displayed incorrectly for 'Name' via address sender format
fixed
Testing a configured personal S/MIME certificate for a sub-identity did not work
fixed
Testing an S/MIME certificate did not work for an old invalid certificate
fixed
Image preview in Insert Image dialog failed with CSP error for web resources
fixed
Reply All button was missing when using a Microsoft Exchange account
fixed
Button label showed "null" when subscribing to network calendars
fixed
Task reminders could fail for tasks without end dates or with shifted due dates
Fixed in beta 3
What’s Fixed
fixed
Subject text of encrypted messages was lost
fixed
Users could not read mail signed with OpenPGP v6 and PQC keys
Fixed in beta 4
What’s Fixed
fixed
Visited links in dark mode did not change color
fixed
Emoticon insertion in compose windows was not functional
fixed
Thunderbird could crash in folder logic
fixed
Visual and UX improvements
