I used to be in a group that use it, and it works very well; we made great use of the mailing list feature, which Proton lacks beyond “contact groups”. The only thing is getting an invitation, which I seem to recall reading they’re not doing any more.

I didn’t see in the “about” what jurisdiction (if any) you are incorporated in. I also don’t see if there’s any encryption at rest.

You only get company names with “Inc.” in the USA as far as I know?