Thunderbird 91.4.0

Thunderbird is a free, open-source, cross-platform application for managing email and news feeds. It is a local (rather than a web-based) email application that is powerful yet easy-to-use. Thunderbird is developed, tested, translated and supported by the folks at Mozilla Corporation and by a group of dedicated volunteers. Thunderbird gives you control and ownership over your email. There are lots of add-ons available for Thunderbird that enable you to extend and customize your email experience.

Thunderbird gives you IMAP/POP support, a built-in RSS reader, support for HTML mail, powerful quick search, saved search folders, advanced message filtering, message grouping, labels, return receipts, smart address book LDAP address completion, import tools, and the ability to manage multiple e-mail and newsgroup accounts.

Thunderbird 91.4.0 fixes:

  • IMAP startup performance improved for accounts with a multitude of folders
  • Thunderbird failed to send messages when configured to use an IPv6 SMTP server by IP address (instead of a hostname)
  • Forwarding messages with attachments sometimes failed
  • Printing multiple messages at once was not possible
  • Non-utf8 news groups were not supported
  • Thunderbird stalled after sending a message with NNTP and SMTP recipients
  • Using Thunderbird with multiple language packs caused high RAM and CPU use and sluggish performance
  • Clicking a "mailto:" started the composer with the default sending identity instead of a configured alternate
  • Drag and dropped text into a plain text message in the compose window was handled inconsistently
  • FileLink messages did not display correctly when viewed in Outlook
  • In account setup, after selecting an extension provided protocol, it was not possible to create an IMAP/POP account
  • Multiday selections were not cleared when changing week viewed
  • 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
  • Calendar Invitation Panel did not scroll when multiple invitations were pending
  • Calendar print dialog did not have a cancel button
  • Various security fixes