This page explains how to use experimental builds for testing the OpenPGP feature in Thunderbird.
Please also refer to the primary OpenPGP in Thunderbird information page.
Background / Precautions / Consequences
Users who are looking for a stable experience with no surprises should only use the official Thunderbird releases. If an issue is not yet fixed in the releases, you'll have wait for it to become available.
If you are willing to experiment, there are several ways to do so, based on your experience and willingness to adopt.
If any of the descriptions below seem complicated, then it's best to wait for the next official 78.x software update.
While we're currently working towards the 78.2 release, the Thunderbird developers might offer experimental 78.x builds every few days, which includes unreleased changes. These intention of these builds is to allow reporters of problems to verify if an issue has been correctly fixed.
However, using these builds requires some skills.
The way you obtain and use experimental builds differs from the usual way you obtain Thunderbird. You will not use an installation program. Instead, you'll download an archive, you'll have to extract the archive yourself, you'll have to know where the extracted folder is, and you'll have to know how to run the experimental Thunderbird from that folder.
Thunderbird supports having multiple sets of configuration settings in parallel. This is called Profiles. If you're using an experimental build, the software might decide to automatically use a separate storage for the Thunderbird settings (a separate Profile). If you want to control which Profile is used when starting Thunderbird, you need to pass the command line parameter -P to Thunderbird. Additional information can be found in this support article: Using Multiple Profiles.
It is important to be aware of which Profile you are running and which software version you are using.
If your primary Thunderbird version is still the stable 68.x version, and if you'd like to continue using 68.x, then you should NOT run an experimental 78.x build with the same profile.
Similarly, if you are already using version 78 as your stable software version, and you'd like to continue to use the same profile with the stable 78.x versions, then you should NOT run any newer build like 79 Beta or 80 Nightly with the same profile.
The reason for this recommendation is, as soon as a you have used Profile once with a newer version, this Profile will remember that it has been upgraded to a newer version. Later attempts to use the same Profile again with an older software version will result in an error message at startup, and the refusal to start the old version.
However, if you have already upgraded your primary Thunderbird to a 78.x version, and an experimental build is described as being a 78.x experimental, then it is safe to use it with the same Profile. However, it might still be necessary to use parameter -P to tell Thunderbird which Profile it should use.
If you are an advanced user, and if you are willing to maintain separate Profiles for the stable and experimental, then you could use regular nightly builds or Beta builds. However, as a consequence, you'll have to perform all configuration steps in the experimental profile, and both profiles will have separate list of keys and settings.
After having said all of the above, below you can find the latest inofficial experimental 78.x build:
Experimental 78.x build from 2020-07-18
Ensure you're aware of the warnings above.