Password-protected boards

We're looking for a feedback board solution which lies in between private and public boards. We'd like the option to share the board URL and a password, and users would use the password to access the website. If we change the password, users would need to put in the new one to re-access the board.

This is important to us because we don't want the boards to be fully public, but we also can't upload our full user segment emails to a 3rd party.