HI Cristian, that workflow I think can work. The client also used this plugin in the past that does what they want:
http://www.johnkolbert.com/project/absolute-privacy/It would be cool if S2 could have the functionality built in, although using the member levels is a good workaround, then I can set all of the viewable content to Level 1. I believe the S2 admin email would also get a welcome email and has the cool S2 widgets too boot, yeah, I'm an S2 fanboy!
User Moderation
The plugin also adds new fields to the registration menu which require the registrant to enter their first and last name, and to choose a password. Newly registered members are given a WordPress role created by the plugin called “Unapproved User” and although they are registered and have a password, they are unable to login until approved.
After registering, the newly registered user is sent an email reminding him/her that they will be unable to login until their account has been approved. The site administrator is sent an email with a link to quickly approve or delete the new user. Once the administrator approves the account the user is sent an email notification. To unapprove a user, simply edit their profile and change their “Role” to “Unapproved User”.
A new tab called “Moderate Users” is created in the “Users” area which allows you to quickly view and either approve or delete all unapproved users. If you approve a user not using the moderation tab they will NOT be sent a confirmation email.