code: def send_registered_email(self, user, user_email, request_email_confirmation):
          
  
          # Verify config settings
          if not self.user_manager.USER_ENABLE_EMAIL: return
          if not self.user_manager.USER_SEND_REGISTERED_EMAIL: return
  
          # The registered email is sent to a specific user_email.email or user.email
          email = user_email.email if user_email else user.email
  
          # Add a request to confirm email if needed
          if request_email_confirmation:
              # Generate a confirm_email_link
              token = self.user_manager.generate_token(user_email.id if user_email else user.id)
              confirm_email_link = url_for('user.confirm_email', token=token, _external=True)
          else:
              confirm_email_link = None
  
          # Render email from templates and send it via the configured EmailAdapter
          self._render_and_send_email(
              email,
              user,
              self.user_manager.USER_REGISTERED_EMAIL_TEMPLATE,
              confirm_email_link=confirm_email_link,
          )
docs: Send the 'user has registered' notification email.