I actually have some instances where we can’t use DiscourseConnect to have shared logins, so like was suggested, we use a webhook to capture the event.
Our existing systems have API calls that can update users in real time, so we filter the hook to just when they confirm the emails and it then automatically updates the other systems.
If your systems support it, that’s probably your best option. If they don’t, you could always have the system just send an email or use the Discourse API to send a group PM to the users who need to be notified in your admin team. 