All mail is typically encrypted in transit with smtps, and Proton mail is encrypted at rest. But that’s true, it’s not e2ee, so I guess they could just scrape it all as it comes in, if they’re not doing so already.
Both companies are based in Europe though so I figure US spying laws don’t apply?
NTsync is not the same as Fsync, it allows for kernel acceleration of NT sync primitives, increasing speed over current wine/Proton builds.