Release Notes

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.

Criteria for closing idle message databases.

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