Host of Webinars can create a Registration Rules to prevent any email addresses that are known to be intruders.

However there could be hosts that do not know about those email addresses and may approved their registration.

It will be best if we can add any known email addresses in Control Hub (for example) and tagged them as intruders/malicious so for every new Webinars registration they will not be able to access.

We have well known fraud email addresses that joined our Webinars but some of the Hosts are unaware - hence the reason if we can blocked it at an Organization level instead of just from the Webinar Registration Rules only.