Submission + - Facebook, Twitter, Google opening URLs in your email (computerweekly.com)
Security firm High-Tech Bridge set up a dedicated server to see which of the services picked up and used a unique URL they added to emails sent through various services. During the 10 days of the experiment, only six services out of the 50 took the bait, but they included four of the biggest and most used social networks: Facebook, Twitter, Google+ and Formspring.