Case Updates Threaded

In vanilla SuiteCRM, does the system allow you to attach an inbound email to a case, and have that email become a case thread in the “case updates threaded” area? I am being told that the only way it can add an update is with the crm Portal. I want to have it so that a customer responds to their case update and that it will keep the thread chain going in that threaded updates area. Is this available in Vanilla SuiteCRM?

Have you looked into “group emails”?