Release Notes

Thunderbird Desktop

Version 91.0.3 | Released August 26, 2021

Check out the notes below for this version of Thunderbird. As always, you’re encouraged to tell us what you think, or file a bug in Bugzilla.

** Thunderbird 91 is only offered as direct download from thunderbird.net and not as an upgrade from Thunderbird version 78 or earlier.** A future release will provide updates from earlier versions.

System Requirements: Details

  • Windows: Windows 7 or later
  • macOS: macOS 10.12 or later (macOS 11.0 for Silicon)
  • Linux: GTK+ 3.14 or higher

What’s Fixed

fixed

Folder icons could be overridden by linked favicons in HTML messages

fixed

Unified folders showed no messages when underlying folders were removed

fixed

Folder pane toolbar did not always persist after restarting Thunderbird

fixed

Compose window attachment pane did not close when disabling signing of an OpenPGP message

fixed

Using "Reply to List" with some list emails incorrectly opened a "no-reply" warning

fixed

Unread message count badge on Windows tray icon did not update after moving messages to the Junk folder

fixed

Account setup UX issues with Exchange autodiscover

fixed

Account settings did not display non-UTF-8 server descriptions correctly

fixed

Thunderbird sometimes sent an unnecessary "SMTPUTF8", causing some servers to reject mail

fixed

No mouseover pop was displayed with event details for non-all-day events in the Today Pane

fixed

Filtering tasks in the Today Pane did not work

fixed

Email based event scheduling displayed the date and time in a format unreadable by humans

Learn What’s Next

Thunderbird keeps getting better. Subscribe to our newsletter and follow us on social media to stay informed.