SmartScreen Filter is designed to help warn you about unsafe websites that are impersonating trusted websites (phishing) or contain threats to your computer. If you opt in to SmartScreen Filter, it first checks the address of the website you are visiting against a list of high traffic website addresses stored on your computer that are believed by Microsoft to be legitimate. Addresses that are not on the local list and the addresses of files you are downloading will be sent to Microsoft and checked against a frequently updated list of websites and downloads that have been reported to Microsoft as unsafe or suspicious. You may also choose to use SmartScreen Filter manually to verify individual sites with Microsoft. When you use SmartScreen Filter to check websites automatically or manually, the address of the website you are visiting will be sent to Microsoft, together with standard computer information and the SmartScreen Filter version number. To help protect your privacy, the information sent to Microsoft is encrypted.
The UNIX philosophy basically involves giving you enough rope to hang yourself. And then a couple of feet more, just to be sure.