Release Notes

Native support for macOS devices built with Apple Silicon CPUs

Thunderbird now operates in multi-process (e10s) mode by default

Latvian language support

New user interface for adding attachments

Enable redirect of messages

Ability to change order of accounts in UI

Allow showing empty CC/BCC rows in compose window

Warning popup when sending a reply to a likely non-existant email address such as "noreply@example.com"

Warning popup when public recipients of a message exceeds threshold

Add support for "X-Unsent: 1" header, to open a saved email in a compose window for editing

Add support for non-ASCII characters in recipient addresses

Context menu to expand mail list pills in the compose window to the list of recipients

Quick Find is now available in the multi-message (thread summary) view

Keyboard shortcuts to access To/CC/BCC fields of compose window

Allow pinning folder views to the Folder Pane

Language packs and dictionaries added to about:support

PDF.js viewer now included in Thunderbird

OpenPGP: "Copy Key Id" option added to Key Manager context menu

OpenPGP: Added config option to disable encrypting saved drafts

Encrypt mail to BCC recipients (with warning that it will expose the recipients in the list of keys)

CardDAV address book support

CardDAV address books automatically detected based on provided user information

Access to Outlook Contacts; To enable, set ldap_2.servers.outlook.dirType to 3; This setting may cause startup delays.

Suggest replacements for discontinued/incompatible add-ons

Chat: Beta-level support for Matrix servers (set chat.prpls.prpl-matrix.disable to false)

Calendar: Remote calendar auto-detection now supported

Calendar: Calendar and category colors now displayed in selection dropdowns

Calendar: "Edit" item added to event context menu

Calendar: Support opening of .ics files by double-click

Calendar: Thunderbird now informs the operating system that it knows how to open webcal: URLs

Calendar: Filter and sort items to be imported in the Import dialog

Prompt to choose the identity of an accepted calendar invite when no identity matches the event attendees list

Support mid: URL scheme for Related Links in calendar event dialogs

Permissions to access calendar and address book are now requested when a GMail account is set up, so that calendar and address book can be accessed without having to re-authorize (see notes)

Calendar: Per-calendar and global notification settings (in addition to alerts set in events)

Tasks: Undo/Redo support for event and task creation and deletion

"Master Password" renamed to "Primary Password"

Renamed "Add-ons" to "Add-ons and Themes" and "Options" to "Preferences"

Account setup moved to a tab

Mail recipients that are not found in any address book will no longer appear in red type; invalid addresses will appear red

Clicking on an already-selected pill in the recipient list will now allow editing the address

Folder pane color scheme overhauled with a focus on readability

Sending backend, SMTP protocol, and LDAP protocol implementations rewritten in Javascript

Sending backend, SMTP, and IMAP protocols now operate only in UTF-8 mode

Sending a message will now fail if any recipients are not accepted by the SMTP server

Error messages from an SMTP server are now displayed to the user

UI Customization controls moved to the View menu

End-to-End Encryption "Advanced Settings" are now disabled when encryption is not configured

Movemail support removed

WeTransfer FileLink provider removed

Enterprise policies updated

Printing UI updated

AutoComplete from LDAP directories now searches by substring instead of left-side match

Support dropped for macOS address book integration

Chat modules and custom widgets are now lazy-loaded to improve Thunderbird startup time

Default IRC server for new chat accounts changed to "libera.chat"

Chat: Image based emoticons replaced with Unicode

Calendar: Opening an existing event now opens summary dialog

Calendar: Default to CalDAV when supported by the server

Thunderbird did not properly handle Self-signed certificates on IMAP servers

Various issues with special and non-ASCII characters in IMAP folders names, especially on Gmail

Drag & drop operations could be disrupted by incoming mail notifications

Dragging a folder from an authenticated IMAP server to a not-yet authenticated server fails

Temporary errors from POP3 servers would cause Thunderbird to stop downloading mail until it was restarted

Favorite Folder view did not maintain UI state between Thunderbird restarts

Saved search virtual folders were not retained after restarting Thunderbird

Thunderbird did not correctly warn about all affected filters when removing a folder

Manually running filters on a maildir folder did not work

Partially downloaded messages displayed in a stand-alone window did not refresh after clicking link to download the rest of the message

An erroneous "Sender" header was displayed in the message preview after viewing certain S/MIME signed emails

Some temporary files created by the message composer were not automatically removed after closing the compose window

Archiving messages from an NNTP account made the target folder unusable

Compose window: The user-configured style for quoted text was not honored

Message headers in compose window disregarded manual resizing when adding additional recipients

Various improvements to new message notifications

A Thunderbird icon pinned to the Windows taskbar reverted to a non-functional placeholder after an update

Various improvements to recipient pills in message compose window

Keyboard shortcut to open the Message Security popup did not work on Mac

Subject column in message lists sometimes showed text from invalid email headers

Account settings: When creating a new account, some already entered settings did not copy to the Advanced Config dialog

Default address book preference was not honored in the contacts sidebar

Import Address Book from CSV did not not allow mapping all available fields

LDAP address books did not display multi-valued attributes

Address Book: Users with LDAP admin rights could delete accounts if trying to delete an entry from an address book backed by LDAP

Some preferences related to an address book were not removed when the address book was deleted

Shortcut for Advanced Address Book Search (Ctrl+Shift+F) did not work on Linux

Radio buttons could not be selected on photo tab of an address card

Windows uninstaller did not always remove all Thunderbird program files

Chat: Double clicking an account type in new account wizard did not select it

Chat account settings did not always save as expected

User nickname colors were not used in chat content

Chat: Multiple system messages did not collapse

Calendar: Reminder details appeared editable when viewing an event

Calendar: HTML rendering in event descriptions restored

Calendar: The toolbar in the invitation details dialog was not honoring the theme colors

Calendar: Various dialog updates

Calendar: Import and export via CSV did not parse years correctly in event dates

Calendar: Event boxes were not always focused when clicked

Dragging and dropping an ICS file to the Today Pane did not populate the "New Event" dialog

Calendar: Reduced flickering effect in Today Pane

Calendar: The time of day indicator line did not update automatically

Location field was not preserved when modifying recurring events stored on a remote calendar

Today was difficult to pick out visually in the month/multiweek calendar views

Columns in Today Pane were not resizable

Calendar event text could render outside the confines of the event block

Event time and event name were not vertically aligned

Improved formatting of event descriptions with long links, such as Zoom invites

RSVP replies to invitations sometimes sent from the wrong email address

Various UI and theme improvements, especially to dark themes

Various security fixes

OTR chat encryption fails on 32-bit Windows builds