Create a Salesforce contact by email, or return the existing one; the contact joins the account company_id, else the first account named company_name when there is one. list_id is ignored: Salesforce has no lists. first_name/last_name are sent as given; full_name is split only when both are missing. Salesforce requires a last name to create a contact: without one the create is a bad_input miss.
Price: $0.00 per unit.
Maximum charge per unit: $0.00.