Hi,
We receive issues via email from our external customers. Therefore our current configuration is the below:

A customer reached out to us because he is receiving email notifications of other customer's issue. He has not been CC in any of the emails, so it does not appear as Request Participant.
I once created an Organization for our project but then deleted it. However all the customers have been added to the Customers section.
What can I do to avoid customer's receiving notification from other customer's issues?
Besides the notifications, I don't want customers being able to view other issues.
Thanks!