Thunderbird 91.0

Thunderbird

Thunderbird is a free, open-source, cross-platform application for managing email and news feeds. It is a local (rather than a web-based) email application that is powerful yet easy-to-use. Thunderbird is developed, tested, translated and supported by the folks at Mozilla Corporation and by a group of dedicated volunteers. Thunderbird gives you control and ownership over your email. There are lots of add-ons available for Thunderbird that enable you to extend and customize your email experience.

Thunderbird gives you IMAP/POP support, a built-in RSS reader, support for HTML mail, powerful quick search, saved search folders, advanced message filtering, message grouping, labels, return receipts, smart address book LDAP address completion, import tools, and the ability to manage multiple e-mail and newsgroup accounts.

Thunderbird 91.0 release notes:

Thunderbird version 91.0 is only offered as direct download and not as an upgrade from Thunderbird version 78 or earlier. A future release will provide updates from earlier versions.

What's new:

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

Changed:

"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
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

Fixed:

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