Thunderbird Desktop
Version 157.0beta | Released September 14, 2026
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 157 beta 3 released September 21, 2026.
System Requirements: Details
What’s New
new
Enterprise policy DisableChat disables Thunderbird Chat functionality
new
Enterprise policy DisableFileLink disables Thunderbird FileLink functionality
What’s Changed
changed
Preference mailnews.headers.minNumHeaders has been removed
changed
Allow viewing remote content in OpenPGP messages encrypted with integrity protection
changed
RNP command-line utilities are no longer included with Thunderbird
changed
IMAP/POP manual config port field is now optional
What’s Fixed
fixed
Ctrl+Shift+K could fail to open the Quick Filter UI
fixed
Status bar could remain active and cause 100% CPU usage after activity ended
fixed
OpenPGP discovery failed to find replacement keys after a key was revoked
fixed
Valid RSA OpenPGP keys could be rejected, preventing encryption
fixed
Sent messages could silently fail to save to the IMAP Sent folder
fixed
Sending message did not fail gracefully with malformed references header
fixed
Thunderbird could hang when waiting for IMAP server greeting during account setup
fixed
Custom OAuth Endpoint Host incorrectly required a full URL instead of a domain
fixed
Message filters could falsely match when evaluating search term failures
fixed
CardDAV address books could fail to sync when no password prompt was needed
fixed
Yahoo emails appeared blank with MIME handlers disabled via mailnews.display.disallow_mime_handlers
fixed
Pending moves within the same IMAP account could make messages disappear
fixed
Inline images could disappear after editing and resaving drafts
fixed
SMTP OAuth2 failed when large access token exceeded command line length limit
fixed
Gmail OAuth2 authentication could intermittently fail on Windows
fixed
Exchange NTLM authentication failed when updated passwords were not saved
fixed
SMTP AUTH LOGIN could fail after username challenges and close the connection
fixed
AppUpdatePin policy did not prevent Thunderbird from updating beyond pinned version
fixed
Recurring events could appear after their configured end date
fixed
CalDAV task body could remain outdated after syncing changes from another client
fixed
CalDAV invitations could fail when accepted before the calendar synced
Fixed in beta 2
What’s Changed
changed
Thundermail built-in add-on updated to v2.0.13
Fixed in beta 3
What’s Changed
changed
Thundermail built-in add-on updated to v2.0.16
