Choose, Visitors, but administrator approval is required. This blocks users to automatically login to the developer portal. When an user registers he will be provided with a message like below.
Once, your backend verification is done, You can set the status of user to active either manually editing user of Drupal APIs exposed using services module. It’s not out of the box but easy to setup. Drupal developer can easily expose activating user functionality to the outside world securely using REST APis.
You can configure Email to send to the user once user is activated in “admin/config/people/accounts” page. See screenshot below.
Thank you @Anil Sagar. We had tried that approach but we found no way to set the user status to active via the API which would stick. Dev portal seems to be master in the sync with edge.
@Thom Linden , Apigee Developer Portal is built on top of famous open source cms Drupal. So, You can leverage any Drupal Contributed module according to your needs. Keep us posted if you have any queries.