Note it!
Leave the email empty to use the shared board password.
We mail you a link to confirm the address. Forget the password later and you can reset it by email from the sign-in tab.
Only works for an account whose address was confirmed. The shared board password is not resettable this way - it is not tied to an inbox.
This link works once, and only for the next hour.
Affects only that one address, and only the mail limit - it grants nobody access to any board.