Of the various settings here, the most important ones are:
- Enable self-registration
- Setting this option will mean that new users can register themselves. It is strongly advised to keep the "let users select their own passwords" UNchecked when choosing this option, as at least all new users will have to have a valid email. This helps in slowing down bot-generated attacks.
- Use email address as login name
- As most people have difficulty remembering login names, it can be good to allow email addresses as logins.