Posteo is mostly just a deployment of RoundCube.
Mind you, I do assume they have deployment scripts and code for handling payments and such, which aren’t open-source.
I also have to say, though, a hosted service using open-source is *nice*, because they will hopeful contribute back to that, but it’s not much beyond that.
You cannot know, whether they actually run the software that they publish in their repository, so auditing the open-source code hardly tells you anything about the trustworthiness of the actual service.




















Hmm, don’t think you should need to compile it yourself? They offer downloads for Windows and macOS, and on Linux, the normal Firefox from the distro sources generally already has this compile flag enabled, as far as I know.
I mean, I actually never had a need for unsigned extensions, so never tried it myself, and obviously I wouldn’t know, if every single distro does it the same.
As for wanting to contribute to the statistics, I do understand that desire. But I believe, for the most part, it’s the user agent that counts. I doubt, they would set that to something else in the unbranded builds…