Edit: When using Tor
Edit: When using Tor
You can either receive an SMS to your phone number, or donate with your card.
Probably related to me trying to signup via Tor.
<quote>
Too many ProtonMail accounts have been created from your connection.
Thus, we are requesting additional verification to ensure you are human and not a spam bot.
Because Tor is frequently abused by spammers, this check may be triggered because of the Tor exit node you are using.
It's unfortunate because it means there's no way that a ProtonMail account can't be tracked to some static identifier (actual IP or phone number).
http://i.imgur.com/bRcPZEU.png
Last time I tried to sign up, "captcha" was not an option, leaving only privacy-invalidating options. It might be dynamic. The criteria for them not displaying "captcha" as an option is unclear.
Unrelated note - that Dropbox link exposes what I assume is your email address. Interesting...