[s777]

I'm not sure how paid Gmail handles data, but at least Fastmail is not from a giant ad company that wants to basically DRM the internet with WEI and generally has an incentive to collect as much data as possible and show ads everywhere. Privacy (against corporations) is one of Fastmail's main marketing points, and considering how it's a smaller paid-only service where being discovered lying about its claims could basically destroy its business, I would trust it more than paid Gmail which will continue to exist despite Google's unethical behavior. It's not end-to-end encrypted though, so it's not perfect privacy-wise, and worse than ProtonMail/Tutanota in that regard.

However, after looking some things up, I just saw that Mailbox.org has a feature called "Encrypted Mailbox" that automatically encrypts incoming emails before storing them (which I somehow didn't see when I was using it since I thought it was similar to FastMail but based in a different country), similar to how ProtonMail/Tutanota work, and I'm not seeing anything similar for FastMail. However, Mailbox.org also supports third party clients and features that FastMail has like email forwarding, unlike ProtonMail/Tutanota, so Mailbox.org actually looks like a better option than any of the others (assuming you trust that they're not secretly storing your emails as they arrive somewhere unencrypted, although they might if forced to by the government).