Greenlight requires unnecessary email validation (invitation-only)

When configured in registration-by-invitation mode, the admins send out an email invitation, which the user can accept to register herself. After that step, the system sends out an email to welcome the newly registered user, in which it requests to VALIDATE the EMAIL ADDRESS. This is a nuisance for the user (in registration-by-invitation mode) and the registration after the first email should be counted as validated.