Release Notes

Thunderbird Desktop

Version 91.4.0 | Released December 7, 2021

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

For more on all the new features in Thunderbird 91, see New in Thunderbird 91.0.

System Requirements: Details

  • Windows: Windows 7 or later
  • Mac: macOS 10.12 or later
  • Linux: GTK+ 3.14 or higher

What’s Fixed

fixed

IMAP startup performance improved for accounts with a multitude of folders

fixed

Thunderbird failed to send messages when configured to use an IPv6 SMTP server by IP address (instead of a hostname)

fixed

Forwarding messages with attachments sometimes failed

fixed

Printing multiple messages at once was not possible

fixed

Non-utf8 news groups were not supported

fixed

Thunderbird stalled after sending a message with NNTP and SMTP recipients

fixed

Using Thunderbird with multiple language packs caused high RAM and CPU use and sluggish performance

fixed

Clicking a "mailto:" started the composer with the default sending identity instead of a configured alternate

fixed

Drag and dropped text into a plain text message in the compose window was handled inconsistently

fixed

FileLink messages did not display correctly when viewed in Outlook

fixed

In account setup, after selecting an extension provided protocol, it was not possible to create an IMAP/POP account

fixed

Multiday selections were not cleared when changing week viewed

fixed

When creating a new event by clicking and dragging the mouse to create a box, the view did not auto-scroll after reaching the bottom

fixed

Calendar Invitation Panel did not scroll when multiple invitations were pending

fixed

Calendar print dialog did not have a cancel button

fixed

Various security fixes

Learn What’s Next

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