Software Update: Mozilla Thunderbird 91.0.2

The Mozilla Foundation has released a second update for version 91 of Thunderbird. Thunderbird is an open source email and newsgroup client, with features such as support for several mail and news accounts, a spam filter, spell checker, and a customizable look and feel. In version 91 has included a warning when an email is sent to a possibly non-existent address, or when there are too many addresses on the public address line. There is also support for CardDAV and there is a native client for a Mac equipped with an Apple Silicon processor.

At the moment it is not yet possible to do an automatic update from version 78 to 91. An existing installation can be updated by manually downloading and running the installation file. The automatic migration will be added in a future version. In version 91.0.2, the following changes and improvements have also been made:

What’s New

  • Tags are now colored in mail filter editor
  • Preference for disabling the unread message count badge on Windows taskbar icon added: mail.biff.show_badge


  • Context menu items related to OpenPGP and attachments are now hidden when not applicable


  • Creating a new account with manual setup failed
  • Recipient autocomplete always preferred the primary email address for a contact
  • LDAP performance improvements
  • Extensions listed on the Recommended Addons did not have a clear way to view details in a browser
  • Status checkmark on View > Calendar > Calendar Pane > Show Calendar Pane was reversed
  • mid: URLs in calendar invites did not open the linked mail message
  • Various theme and UX fixes

Version number 91.0.2
Release status Final
Operating systems Windows 7, Linux, macOS, Windows 8, Windows 10
Website Mozilla Foundation
License type Conditions (GNU/BSD/etc.)