However, I should add that if the intellectual property was collected BY the "employee, parter, etc." themselves as
independent consultants while on contract with the "company" that the contact information (NOT sales data) could legally be retained by that independent consultant on the grounds that they are personal contacts and were gathered for that consultant's own business and shared with the "company" at the time of sale.
Again, IMO. Legally in a court there would have to be more information as to the circumstances, technique, and conditions of the gathering of that information.