How can pictures that are sent in an email help the sender identify your computer?

Sometimes my software will block the pictures along with a warning to tell me of that risk and asks if I want to download them or not. Sometimes they are just smileys. Is that because some smileys have spyware?
How can pictures that are sent in an email help the sender identify your computer?
It is usually because the pictures are located on a server and they log who hits the server, so it will give them your IP address.
Reply:Any file can be infected with malware, including image files and Smileys. Some malware "phones home" with your personal data. When your browser gives you this kind of error message, take heed!!!





Download the file, but don't open it. Scan it with your Anti-virus app, AVG, Norton, etc. If it is virus free, then you can safely open it. No guarantees though, Anti-virus tools are only 99.99% effective, at best. If it is NOT virus free, then delete it.





I personally do NOT trust online Virus scanners, they're only 99.99% effective, at best, TOO.
Reply:No, it's just a safety precaution built in to protect users from porn, etc...