Hi,
I created a project so that we can track all the external customers emails received in just one place. I selected the below options:

Later on I created an Organization for the project and inserted all the external customers emails so that then I would be able to easily automate assigning issues to an agent according to the customer's email address.
However we then received an email from a customer saying he was able to view other customer's issues, and that is a problem for us. I proceeded deleting the Organization.
Is there something else I can do to avoid customers seeing other customer's issues or now that I deleted the Organization they should only be able to look at their own tickets?
Thanks in advance!