Just a heads up that registering for a new account here https://en.nostalrius.org/register wouldn't work with my own personal email server.
When I tried my own email account and hit register it just informed me that it sent the email. When using a gmail account the catpcha actually displayed images for me to select.
Is there a whitelist of domains you can register with? This is more of a heads up and not sure if it was intentional behavior.