The Account Registration field-set controls how people obtain accounts on a Yioop installation. Its dropdown chooses one of four possibilities:

• Disable Registration: people cannot register themselves; only the root account can add users. With this chosen, the Suggest A Url form and its link on the tool.php page are turned off as well. Every other choice leaves that link on.
• No Activation: an account is active as soon as the person signs up.
• Email Activation: after registering, the person must follow a link sent to them in a separate email before the account becomes active.
• Admin Activation: after registering, an account holding the admin role must activate the person before they can sign in.

Choosing Email Activation means Yioop has to be able to send mail. How it does that is set apart from here, in the System Emails field-set on the Server Activity page, since Yioop sends mail for more reasons than registering: ballots, notifications and bulk mailings go the same way. That field-set says whether Yioop sends with its own built-in client or through somebody else's mail server, whether a message waits for the Media Updater or goes during the request, and which address it is sent from. See the System Emails help page beside it.

Nothing else on this field-set concerns mail. What a new account may do once it exists is set by the roles it is given, on the Manage Roles page.