Mozilla Thunderbird is a free and open-source, cross-platform email client, news client, RSS, and chat client developed by the Mozilla Foundation.
Thunderbird eventually chose to use Enigmail and its implementation of OpenPGP public key email encryption. Then in October 2019, the Thunderbird blog announced that Thunderbird 78 “will add built-in functionality for email encryption and digital signatures using the OpenPGP standard.”
Thunderbird 78 emerged in July 2020, and late in August Thunderbird contributor Kai Engert posted:
We have released support for OpenPGP email in Thunderbird version 78.2.1. Marking fixed.
Enigmail to Thunderbird’s OpenPGP migration
Unlike Enigmail, OpenPGP in Thunderbird 78 does not use GnuPG software by default. This change was necessary to provide a seamless and integrated experience to users on all platforms. Instead, the software of the RNP project was chosen for Thunderbird’s core OpenPGP engine.
The traditional Enigmail Add-on cannot be used with version 78, because of changes to the underlying Mozilla platform Thunderbird is built upon. Fortunately, it is no longer needed with Thunderbird version 78.2.1 because it enables a new built-in OpenPGP feature.
If you’ve been using Enigmail before you’ll be happy to know that they added a very simple automated migration routine. When you first start Thunderbird 78, with its native OpenPGP features, Enigmail will popped up a tab with a “Migrate” button on it.
Updating to Thunderbird 78 is highly recommended to ensure you will receive security fixes. No more fixes will be provided for Thunderbird 68 after September 2020.