Starting from 126.96.36.199, Administrator can decide whether On-site and E-mail notifications are ON or OFF by default for new members. You can set that in the backend of your site. Navigate to WP Admin -> PeepSo -> Configuration -> Notifications
Administrators can disable ALL e-mail notifications for a given user. You can set that in the backend of your site.
Navigate to WP Admin -> Users
Click Edit user you want to disable their E-mail notifications and then find: Unsubscribe this user from all e-mail notifications
Click, and that user will have their e-mail notifications disabled.