What you need to know about Facebook sneakily swapping users’ default email addresses to @facebook.com
Have you checked the contact information you list on your Facebook profile? Chances are that it’s now listing an @facebook.com email contact address for you.
Learn how to change your settings to make the email address invisible, and to control who can message you.
Story added 26. June 2012, content source with full text you can find at link above.