When a user signs up to a membership level, you can prevent them from using that membership until they validate their email address. This is useful in preventing spam registrations.
This ability is controlled on each membership level you define. Thus, you can require it for free memberships and not require it for paid memberships.
It is disabled by default. To enable it:
Now, when a user signs up for that membership, they will be required to click a link that is present at the top of their standard confirmation email before they can use their membership.
An admin can validate the user manually:
To resend the validation email: