To clarify:
ProtonMail. I don’t hate it, but their choices in what to monetize is bizarre to me, like the ability to make more folders than three, you have to pay to have more folders. Also, it’s not a perfect mail system, you’re going to not get or be able to send 100% of mail because there are mail services people or businesses use that simply don’t register when using ProtonMail.
In an age where there are tons and tons of things out there that is a subscription, paying for the ability to have more features that have been normalized would turn off some people.
Email is de facto not private/secure without adding additional layers to it, so using services like ProtonMail or Tuta are putting lipstick on a pig. They give a false sense of security and privacy that just doesn’t exist without a ton of additional overhead and opsec. Unless you plan to only email other Proton accounts, or use janky one-time password secure messages, your email isn’t E2EE, it’s just encrypted on Protons servers which is table stakes for most paid mail services. They are marketing something that just can’t fully work in the real world. You also then make a ton of trade offs like very limited client support (especially on mobile), and can’t even use S/MIME for compatibility with enterprise secure mail solutions.
To be clear, I think it makes sense to pay for something as critical as email so you aren’t the product, as well is using your own domain for portability. But I don’t recommend folks buy into the false security and privacy promises of services like Proton for email/calendaring.