I agree that your advice is probably a good idea in general and most people shouldn't enter sensitive info into random websites. However, I can't think of any feasible way to link an IP address to an email address. They aren't related to each other in any way and IP addresses change often anyway. I also viewed the webpages source code (briefly) and I didn't see any obvious trickery or calls back to the server. Just in case though, I didn't actually use my exact password. I changed minor things that wouldn't affect the results (such as an 8 to a 9 or a "b" to an "r"), but render the "password" useless.