Facebook replaced the email address users chose when they signed up and changed it to a facebook.com address. The Facebook email accounts allow users to communicate with outside email addresses via Facebook.
The changes were first pointed out by bloggers over the weekend and publicized by media outlets Monday, leading to gripes from users, usually on their Facebook pages.
The company said in a statement in April that it was "updating addresses on Facebook to make them consistent across our site."
Facebook spokeswoman Jillian Stefanki said the site is also rolling out a setting that allows people to decide which email addresses to show on their pages.
"Ever since the launch of timeline, people have had the ability to control what posts they want to show or hide on their own timelines, and today we're extending that to other information they post, starting with the Facebook address," Stefanki said in an email late Monday.