Thunderbird 78.3.1 [Update]

Thunderbird

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 78.3.0 changes:

OpenPGP: Improved decryption performance with large messages
OpenPGP: Do not show external key UI when disabled by preference
Account setup wizard will now open a popup when connecting to a server with a self-signed SSL/TLS certificate
Installation of "legacy" MailExtensions now disabled
Reply-To header moved in compose window; now appears under From header
Calendar: Sidebar UI improvements

Fixes:

Selecting "Cancel" on the Master Password prompt at startup incorrectly reported corrupted OpenPGP data
OpenPGP: Creating a new key pair did not automatically select it for use
Dragging & Dropping recipient pills resulted in lost pills when an error was present
Spellcheck suggestions were unreadable in dark theme
Calendar: Multiple password prompts opened
Linux Distributions: UI was not rendered completely when built without updater
MailExtensions: browser.folders.delete failed on IMAP folders
Various security fixes

Known issues: