This is what I was actually thinking of, not the Guard feature. It's supposed to encrypt your entire mailbox but it also works with third party clients with some extra setup.
sudoer777
Nowadays I would recommend Zen Browser + uBO over Brave which has a nice user-friendly UI and supposedly disables telemetry. Before Zen Browser, disabling the crap Brave comes with takes a similar amount of effort as tweaking Librewolf's aggressive privacy settings, but one of them is actually privacy focused and the other is run by a shady ad crypto company with a shady news feed that keeps pushing Fox News and a homophobic CEO. For mobile there's Cromite.
OpenAI was also a non-profit until a few months ago
At least GrapheneOS isn't something I'd pay for
I use a custom domain for basically all emails since I care more about portability than anonymity. Each account gets its own address, and if a site gets hacked and I start getting spam then I know which one it was. If I really wanted anonymity for something then I would use a randomly generated masked email.
privacytools.io is full of affiliate links and PG has shit tech bro recommendations like Brave browser
Also custom domain if you don't need anonymity (using it to track spam) and want to be able to easily switch providers
Riseup and Disroot are run by collectives, Tuta uses a similar business model to Proton, Mailbox.org + Guard looks decent as well and more open than either Proton or Tuta
It's not E2E encrypted unless you're using PGP or emailing another Proton user, which is basically nobody for most people. They do encrypt your email when it arrives in a way that is supposed to make them inaccessible to them (which is more than what most email providers do), so you'd need to trust that they're not intercepting your emails and storing them somewhere unencrypted. Stuff like SimpleX/Cwtch/Signal is E2E encrypted though by default so their security is a lot better
Tuta is used by the CIA for people who are afraid of Proton having ties with the CIA
I was on a trip for a few weeks to visit family, and just a few days after I got there my server went down and I lost access to all my stuff (I'm about to fix it when I return tomorrow). Stuff like that is why I will never self-host something as critical as email
Also Hexbear and Lemmygrad were populated by r/chapotraphouse and r/GenZedong users respectively when those subreddits got banned, which happened before the main Reddit exodus that populated instances like .world