Having consistent uptime and not locking broken IMAP behind a paywall would beat Tuta.

I have a proton subscription (although I am in the process of switching to fastmail since that better suits my needs) but I think “privacy respecting email” is a fool’s errand and increasingly a red flag. In a lot of ways, it is no different than a VPN: They can say whatever the hell they want. If you are in a situation where you are trusting them then you have already made a mistake.

Proton et al ARE awesome because you can get a mostly functional email for free without any other identification (mostly functional in that a lot of services put the proton domains on a spam list… because anyone can get a burner). But if you are sending ANYTHING sensitive, you want to be encrypting that. And you want to do that in a way that is not asking the company to do it for you.

So as long as thundermail doesn’t require a phone number or some other form of personal ID to make an account: f’ing A. After that it is just a question of their support for IMAP et al (highly probable considering… Thunderbird) and what it costs to use your own domains.