What’s New

• Messages are automatically adapted to dark mode with a quick toggle in the header.
• New “Appearance” Settings UI to globally control message threading/sorting order.

What’s Changed

• Criteria for closing idle message databases.

What’s Fixed

• Thunderbird Release channel was not displayed in “About Thunderbird”.
• Crash could occur when shutting down during MAPI send.
• The error message for compacting a corrupted local folder was not useful.
• Deleting or detaching attachments in a saved .eml file appeared to work but failed.
• On HiDPI screens, clicking addresses in the header could show popup off-screen.
• Opening an .EML file in profiles with many folders could take a long time.
• Some messages may have been threaded incorrectly in unified folders.
• Unified folders could become unusable instead of being automatically rebuilt.
• Folders at level 3+ were not auto-discovered when IMAP subscriptions were ignored.
• New subfolder did not inherit parent view, sort order, sort type, or columns.
• With “Fetch headers only” enabled, messages could not be sorted by size.
• Selecting starred messages did not update immediately.
• Marking a unified folder as favorite did not show it in favorite folders.
• Users with many folders experienced poor performance when resizing message panes.
• The UI could falsely report a message as encrypted when a null cipher was used.
• Search messages dialog list could not be sorted by clicking the header icon.
• Sending to multiple SMTPs could fail silently due to missing address book.
• “Replace” button in compose window was overwritten when the window was narrow.
• Changing the UI font size did not apply to some dialogs.
• Deleted Gmail messages stayed visible until compact/expunge, despite settings.
• Export to mobile did not work when “Use default server” was selected.
• Account settings menu could be loaded twice.
• Account Settings updated font size were not reflected in the content frame.
• Add-ons: Context menu entries were incorrectly aligned.
• Middle-click autoscroll cursor appeared without arrows instead of expected design.
• Some functionality was missing for newsgroup messages opened from a file or URI.
• Notifications for new mail were not showing for IMAP.
• Message and folder lists could display incorrect line spacing after restart.
• Clicking a ‘mid:’ link could clear the thread pane and cause errors.
• Release channel incorrectly showed What’s New page after update.
• “Save Link As” was not working in feed web content.
• Sort indicators were missing on the calendar events list.
• Visual and UX improvements
• Security fixes