First of all...
Why does an email service need a chatbot, even for business? Is it an enhanced search over your emails or something? Like, what does it do that any old chatbot wouldn't?
EDIT: Apparently nothing. It's just a generic Open Web UI frontend with Proton branding, a no-logs (but not E2E) promise, and kinda old 12B-32B class models, possibly finetuned on Proton documentation (or maybe just a branded system prompt). But they don't use any kind of RAG as far as I can tell.
There are about a bajillion of these, and one could host the same thing inside docker in like 10 minutes.
...On the other hand, it has no access to email I think?