[BoppreH]

That's a good point, these problems are not easy to solve. But they should be solved.

For example, the user types "7" into the UI control. The UI control knows it's supposed to hold a number, so it has methods that return the parsed number (done by the OS, very carefully), or an error to the user.

Similarly, you don't send the product name, but the ID of the product the user selected from their fuzzy search. I would go as far as using this technique for the email too.