Thunderbird Desktop
Version 153.0beta | Released June 17, 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 153 beta 10 released July 15, 2026.
System Requirements: Details
- Windows: Windows 10 or later
- Mac: macOS 10.15 or later
- Linux: GTK+ 3.14 or higher
What’s New
new
Unified folders now display account color indicator with account name tooltip
new
OAuth login for mail accounts now opens in default web browser
new
Thundermail services can now be used without installing an add-on
new
OAuth responses now verify issuer fields and reject missing required issuers
What’s Changed
changed
Removed Odnoklassniki chat setup and directed users to XMPP configuration
What’s Fixed
fixed
Ctrl+S did not save PDF attachments opened in Thunderbird tabs
fixed
TLS errors incorrectly reported all unknown failures as untrusted certificates
fixed
Thunderbird could crash during shutdown
fixed
Old IMAP profile migration deleted INBOX and other mailbox files
fixed
Space bar did not scroll in PDF attachments opened from emails
fixed
'Search Messages' shortcut (Ctrl+Shift+F) failed in standalone message window
fixed
Folder location widget used non-localised name
fixed
Empty confirmation dialog when more messages opened in tabs than mailnews.open_tab_warning
fixed
Removing tags from IMAP messages could fail and tags reappeared after refresh
fixed
Global search failed to display inaccessible messages found in local folders
fixed
Numeric subfolders were sorted alphabetically instead of naturally
fixed
Virtual folder folder-picker showed unlabeled IM account as selectable folder
fixed
Apple Mail OpenPGP emails failed to decrypt due to hidden recipient key ID
fixed
OpenPGP import of public key with experimental packets failed with unclear error
fixed
Performance issue when decrypting encrypted messages
fixed
Opening messages with OpenPGP keys was slow and blocked the UI for large keyrings
fixed
OpenPGP key refresh failed when fingerprint lookup returned multiple results
fixed
Invalid S/MIME encryption certificate caused misleading send errors
fixed
Esc cleared quick filter pin after changing folder
fixed
Thunderbird could crash when using Find and Replace All
fixed
Compose window remained open when delayed sending was enabled
fixed
Account hub showed connection security instead of actual authentication method
fixed
Account Hub GSSAPI autoconfiguration incorrectly prompted for a password
fixed
New identity dialog lacked reply-matching and end-to-end encryption settings
fixed
Account Hub manual EWS setup lacked OAuth authentication option
fixed
Thunderbird could fail to shut down cleanly during active OAuth requests
fixed
Account Hub kept OAuth selected after changing to hostname without OAuth support
fixed
Account Hub showed a false error when returning from EWS manual configuration
fixed
Account Hub autodetect wrongly prompted for a password when auth was unavailable
fixed
Redirected CardDAV URLs resolved relative URLs against the wrong host
fixed
Auto-compaction could corrupt database and cause crashes during syncs
fixed
NNTP server with invalid TLS certificate could not be added to certificate exceptions
fixed
Sent message in EWS account showed message as unread in the sent items folder
fixed
EWS NTLM authentication triggered login failures despite successful syncs
fixed
Saving inline Exchange images used incorrect filenames and file types
fixed
Cancelled message send could not be retried and hung with SMTP timeout errors
fixed
EWS folders failed to show new mail notifications until the folder was selected
fixed
Corrupted NNTP account data caused excessive memory use and startup crash
fixed
Multiple selected IMAP folders could not be moved or deleted together
fixed
Non-Latin IMAP keywords were lowercased and encoded incorrectly as MUTF-7
fixed
Message tags were lost when moving folder from local folder to IMAP folder
fixed
Removing a chat account threw an exception and failed to clear the UI
fixed
Calendar invites were incorrectly marked processed after calendar sync completed
fixed
ICS event comments were not displayed in Thunderbird event details
fixed
Visual and UX improvements
Fixed in beta 2
What’s New
new
Enable the "Sign in with Thundermail" button in Account Hub
What’s Changed
changed
Update Thundermail system add-on to 1.9.0 and additional fixes
What’s Fixed
fixed
Interrupted external OAuth2 setup required restarting Thunderbird
Fixed in beta 3
What’s Fixed
Fixed in beta 4
What’s New
new
Added configurable logging to Thundermail with version-prefixed console output
What’s Fixed
fixed
Primary Password policy was detected but not enforced for saved account passwords
fixed
Copying one recurring event occurrence failed to set the date when pasted
fixed
Folder pane could not be horizontally resized in additional 3-pane tabs
fixed
Forwarding some Apple Mail messages incorrectly attached inline text as a file
fixed
Message Filters 'Run Now' button could stay disabled after filter runs or mail checks
fixed
Reply All button was missing for some EWS messages with multiple recipients
Fixed in beta 5
What’s Fixed
fixed
Yahoo OAuth setup hung after browser sign-in and failed to add account
fixed
Thunderbird could crash when copying an empty list of messages
Fixed in beta 6
What’s Fixed
Fixed in beta 7
What’s Fixed
fixed
EWS users could not permanently delete individual Trash messages
fixed
Thundermail system add-on sessions expired instead of automatically refreshing
Fixed in beta 8
What’s Changed
changed
Thundermail built-in add-on updated to V2.0.3
What’s Fixed
fixed
QR exports with SMTP passwords generated invalid data for Thunderbird for Android
fixed
Thunderbird could crash when completing folder copy/move
Fixed in beta 9
What’s Fixed
fixed
Compose with PDF attachments opened PDFs instead of creating a new email
fixed
New mail alerts appeared incorrectly sized or positioned on some multi-monitor setups
fixed
Attachments opened via -compose on Windows could use incorrect filenames
fixed
Ctrl+Enter opened attachment instead of sending the message
fixed
Virtual folders failed to preserve the online search setting
fixed
View Source context menus became transparent and difficult to read
Fixed in beta 10
What’s Fixed
fixed
Sending Message dialog got stuck on "Filter complete." after successful send
