I am glad to announce, the electron based standalone app has landed!
Originally it was planned to have both the Thunderbird add-on and the app side by side. And gradually migrate to the app.
But the last Thunderbird updates created a devastating hit on the add-on. Even very basic things are broken. And it will most likely get worse for the future when Thunderbird drops support for classic add-ons. This will be then most likely the end for this add-on.
The app is based on electron and is shipped with his own runtime environment. Which makes it independent from Thunderbird and thus way more robust and stable. The downside is the app is large. But it is definitely better having a large standalone application than an dysfunctional Thunderbird add-on.
A special highlight of the app is the shiny new HTML based responsive UI. So give it a try and let me know what you think.
The app is mature but still a pre-release, so expect some glitches.
There is no installer, just download, unzip and run the sieve executable.
The app does not update automatically to a newer release.