In the customer portal, customers only see tickets connected to the email address they logged in with. These are the tickets they raised, the tickets your team created for them, and any ticket where their email address was in CC on the original message or on a reply.
This means anyone you add in CC on a reply can log in and read the whole ticket, including messages sent before they were added.
Customers don't see tickets raised by their colleagues, even when those colleagues are added to the same company in NeetoDesk.
The ticket lists
The portal's home page, Your tickets, has two lists. Open tickets shows tickets with any status other than Closed. Closed tickets shows the tickets with the Closed status. Tickets marked as spam or moved to trash are left out of both lists.
Each ticket in the lists shows its subject, status, created date, and last updated date. The most recently updated tickets appear first.