Comment by alttab
16 years ago
If Bill puts his new e-mail address on Facebook - he has effectively chosen to give it away. It is now information that all of his friends own.
Choose your friends carefully, but choose the data you put on Facebook with even more discretion.
You can make email addresses private on Facebook, so that none of your friends can see them. However, people who already have your email address can use it to find you.
Facebook and Google are using those email addresses for very different purposes: Facebook uses them to identify the profiles of your contacts (the user id is the lasting identity) whereas for Google the email address itself is the relevant identity.