

Allow pinning folder views to the Folder Pane.Keyboard shortcuts to access To/CC/BCC fields of compose window.Quick Find is now available in the multi-message (thread summary) view.Context menu to expand mail list pills in the compose window to the list of recipients.Add support for non-ASCII characters in recipient addresses.Add support for "X-Unsent: 1" header, to open a saved email in a compose window for editing.Warning popup when sending a reply to a likely non-existant email address such as Warning popup when public recipients of a message exceeds threshold.Allow showing empty CC/BCC rows in compose window.Ability to change order of accounts in UI.New user interface for adding attachments.Thunderbird now operates in multi-process (e10s) mode by default.

Native support for macOS devices built with Apple Silicon CPUs.A future release will provide updates from earlier versions. Thunderbird version 91.0 is only offered as direct download and not as an upgrade from Thunderbird version 78 or earlier.
