In the email field, enter the local-part of the email address and add "+" [org name] before the domain. Always stick to yourname+[orgname]@address.com naming convention for any Admin users being adding using this method
Once the invitation is sent out, the "+" [org name] will be stripped out of the email so it will arrive at the staff member's real email address. The invited admin can click through the invitation email to finish setting up the account
The account will not appear on the Administrators page within the specified org until the invited user has clicked through the email and completed the registration.
In order to use the same email address to maintain multiple admin accounts across numerous orgs., admins will need to always enter the unique yourname+[orgname]@address.com email address when logging in to the CB Defense console
Additional Information
The solution will only work if the email service supports "+something" aliases