Whether you knew it or not, Facebook Inc. has changed your default email address. 

Over the past few weeks, Facebook has been changing the default email addresses displayed on users profiles to their @facebook.com address, an account every registered Facebook user has, but many don't use. 

Bloggers and tech writers noticed the change recently, which caused some to criticize the company.

"Facebook silently inserted themselves into the path of formerly direct, unencrypted communications from people who want to email me. In other contexts, this is known as a Man In The Middle (MITM) attack," tech blogger Gervase Markham said in a blog post. "What on earth do they think they are playing at?" 

Facebook responded by saying the change was to make things consistent with its new Timeline feature.  

Users who want to change the setting can do so by editing their Facebook contact information.