I had created an account a while ago to give Auth0 a shot and see if it would meet my needs. I decided to revisit it recently but when I login with my typical email address, I am prompted to create a new *.auth0.com domain. However, the domain I know I would have selected (and is highly unlikely anyone else would have used) is unavailable.
Therefore, I believe I must have used a different email address to create my previous account. If possible, I’d like to figure out which email address I used so I can login and use the .auth0.com domain which matches my Site’s domain. However, I have used the password-reset feature with every email address I can think of and have received no prompts to reset my password on any of them.
I’m afraid this is a complex situation because of the information that can or cannot be disclosed around email addresses and associated tenants.
Given that you already covered the username/password (Auth0 specific credentials) scenario for every email address you can think you may have used one possible explanation would be that you previously used a social provider to login.
There’s no automatic linking of accounts by email address so if you login with user@example.org (Facebook) this will be a completely different identity to user@example.org (GitHub) or Auth0 specific credentials with same email address.
This may be time consuming, but if you really want to try your luck you may want to try also the social provider logins.