Notify Administrators whenever a new administrator is setup

Zendesk does this and seems a nice safety feature. Here is a sample email from them:

This is an automated message from Zendesk to keep you informed of major
changes made to your settings.

A new admin user has been added to your account by Andrew Ardron (aca@prospectsoft.com).

Name: Dan Bryant
Email: djb@prospectsoft.com

Please contact your account's administrator if you think this message is mistaken.

This email is a service from ProspectSoft. Delivered by Zendesk