Release Notes

Thunderbird Desktop

Version 91.1.0 | Released September 7, 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 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 Changed


VCard attachments now sent with "text/vcard" instead of "text/x-vcard"

What’s Fixed


Thunderbird registered Accessibility Handlers using same GUIDs as Firefox, causing performance issues for NVDA users


Focus lost when reordering accounts by keyboard in the Account Manager


Account setup did not use provider display name for setting up calendars


Various theme and UX fixes


Various security fixes

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