Final answer:
Sales made through mail order are not exempt from a sales tax.
Step-by-step explanation:
A sales tax is a tax assessed on an item bought in a store. It is collected by the government to help pay for services such as schools, libraries, roads, and police and fire protection.
The statement in the question, 'Sales made by mail order are not exempt from the application of a general sales (or use) tax' is referring to the fact that sales made through mail order are not excluded from being subject to a sales tax.
For example, let's say you purchase a book through mail order. If your state has a sales tax of 5%, you would have to pay an additional 5% of the book's purchase price as sales tax.