Like I said, I was paged in the middle of the night because protonmail accounts were being created at a rate of hundreds per second to use our hosted free trial to mine crypto. So I blocked the domain name. I'm not saying this is wonderful or anything, but it is what I had to do at the time.

I see that my post got massively downvoted, but this is the thought process for people administering things. You get overrun and then you make a rash decision. I basically had the choice to to block protonmail from using the free trial, eliminate free trials, or require everyone in the Universe to type in a credit card, pay their bill and not dispute the charges for 90 days. I chose the first one. Free trials continued for the vast majority of the world. But hey, we ended up deciding not to do the cloud offering (in part because of this), so maybe I fucked up that decision.

I'll definitely be thinking about fraud/risk from day 1 the next time I do a cloud service, so that innocent users of email domains abused by fraudsters are not unfairly discriminated against. I didn't do it the first time, and that's on me. I just wanted to share the thought process of someone in the trenches; not make a value judgement of your email provider! You as an individual user of some service can't be held accountable for the actions of the other users of that service. I get that and I feel bad about what I did at the time.

But, having been where the UK government is, I totally get where they're coming from. That's all I wanted to say. Protonmail can do some vetting of their customers, so that their emails become more trustworthy, if they feel like it. That would make their product more valuable for all the legitimate users.