Thunderbird Desktop
Version 154.0beta | Released July 29, 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 154 beta 3 released August 5, 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
Preview functionality for attachments on macOS
new
CMS message with AuthEnvelopedData can be decrypted properly in Thunderbird
new
Global search results can open in list view by default with new setting
new
"Copy To" folder context menu added for message/rfc822 attachments
new
Optional system tray mode that hides Thunderbird when the last window closes
new
Support for dragging message/rfc822 type MIME attachments to folder tree
new
Microsoft Graph enabled for Microsoft 365
What’s Fixed
fixed
Remote content warnings appeared despite sender block exceptions being applied
fixed
Collapsed saved-search folders did not deselect their subfolders
fixed
Some signed emails could enter an endless rendering loop in the message pane
fixed
Server-designated special folder flags could be removed until restart
fixed
Messages could render excessive trailing blank lines
fixed
Copying a message subject included the "Subject:" label in copied text
fixed
Moving IMAP folders to Local Folders could delete messages after copy failures
fixed
7-bit clean unobtrusive signature payloads were unnecessarily base64 encoded
fixed
OpenPGP sending failed when an older accepted key had no valid encryption subkey
fixed
Account setup tried local-part usernames before full email addresses
fixed
Read-only CardDAV address books were incorrectly treated as writable
fixed
Blank 1970-dated messages could appear from incomplete message file copies
fixed
Opening drafts or templates with invalid quoted-printable data could crash Thunderbird
fixed
Thunderbird could crash when inserting a message header into database cache
fixed
IMAP repeatedly notified for messages already read on another device
fixed
Dragging EWS search folders to Trash caused Thunderbird to crash
fixed
Folder compaction displayed incorrect disk space recovery estimates
fixed
Custom OAuth settings for EWS account overwrote original account's settings
fixed
Thunderbird could crash when going offline with an active IMAP IDLE connection
fixed
Thunderbird could crash while running online mail search
fixed
Exchange accounts could show repeated false login failures during authentication
fixed
Expired newsgroup articles showed an insecure "click here" purge link
fixed
IMAP attachments appeared empty after messages were moved by filters
fixed
Default special-folder names could reference nonexistent server folders
fixed
Thunderbird macOS fell back to Software WebRender after GPU process launch failures
fixed
New RSS subscriptions used updated dates instead of published dates
fixed
Thunderbird could crash while discovering IMAP folders
fixed
Calendar sort order was not preserved across Thunderbird restarts
fixed
"All calendars are disabled" banner reappeared after enabling a calendar
fixed
Dismissed CalDAV reminders could permanently stop future event notifications
fixed
Read-only CardDAV calendars were incorrectly treated as writable
fixed
CalDAV sync failed when server responses used UTF-16 encoding
Fixed in beta 2
What’s Fixed
fixed
New Message and New Event buttons were unreadable in right-to-left locales
Fixed in beta 3
What’s Changed
changed
There are no Thunderbird changes requiring release notes in this release
