Facebook has been criticized after it replaced users’ email addresses listed on the site with its own @facebook system.
The company claimed that it has acted to make communications more “consistent” across the social network.
But many observers feel that this is part of plans to draw people into using the Facebook email system rather than the services of other providers.
Newly-listed Facebook would benefit from this by driving more traffic to its page and therefore boosting advertising revenue.
Facebook replaced the email address users chose when they signed up with a facebook.com address.
The Facebook email accounts allow users to communicate with outside email addresses via Facebook.
Users are free to restore their former email addresses.
Facebook first announced plans for the move in April, although the news attracted little attention at the time.
“We are providing every Facebook user with his or her own Facebook email address because we find that many users find it useful to connect with each other, but using Facebook email is completely up to you,” said a statement from the company.
Emails sent to @facebook.com addresses appear alongside posts sent via the network’s internal message system, allowing users to pick up both types of communication from the same place.