When you create accounts, you assign the following attributes to each top level account, sub account, and sub sub account:
Account password: You can create a password to restrict access to accounts, sub accounts and sub sub accounts. If an account is password-protected, you must enter the password to edit or process mail against the account. Passwords are case sensitive, can be alphanumeric and must be four characters in length.
NOTE: Account passwords must be turned on before they can be added to accounts.