NEW YORK (AP) - In yet another change that upset users, Facebook has replaced the email addresses users chose to display on their profile pages with (at)facebook.com addresses.

Previously, users may have displayed their personal yahoo.com or gmail.com address to let people know how to contact them outside of Facebook. Now, Facebook has hidden those addresses and put a Facebook email listing in its place.

The changes raised users' suspicions. By hiding other email addresses Facebook can keep its already-captive audience even more captive. Sending an email to a Facebook.com address will land the email in the messages section of a user's Facebook profile. The more people use Facebook to communicate, the more the company can target ads based on the conversations they have on its platform -just as Google targets ads to Gmail users based on text in their emails.

"They've got an email service that no one is using," said Forrester analyst Nate Elliott. Getting people to send emails to and from Facebook deepens people's connection to the site, he added. "This is a way of encouraging use - it's just a rather crude way."

The email change was first pointed out by bloggers over the weekend and publicized by media outlets Monday. The exposure led to gripes from users, mostly on their Facebook pages and on Twitter.

Users who are bothered by the change can reset their profile. Facebook didn't delete the previously displayed email addresses. So, to revert back to the original address, click on the "about" section of your profile. Once there, look for "Contact Info" and click on the edit icon on its right hand corner. There, you can change who can see your email address and which email addresses they can see.

The Facebook.com email address allows users to communicate with outside email addresses via Facebook, but it's unclear how many people use the feature. Popular as it has been with more than 900 million monthly users, Facebook messages and posts have not replaced email, texting and other forms of communication.

The company gave its users Facebook.com email addresses back in 2010, but only in the last few months has it begun to display them on people's profiles. In an announcement that went largely unnoticed, it said in April that it was "updating addresses on Facebook to make them more consistent" across the site.

To Facebook consistency meant switching everyone to a Facebook.com address. Over the weekend, Facebook added a feature that lets users change what contact information is displayed on their Timeline directly from the Timeline - without having to go into their account settings. In rolling out this change, the company defaulted everyone's displayed address to Facebook.com.

"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," Facebook spokeswoman Jillian Stefanki said in an email late Monday.

Menlo Park, Calif.-based Facebook is well known for making changes to its website that occasionally irritate users. Some users are still holding off on switching their old profile pages to the Timeline, which lists users' shared life events, updates and photos in chronological order, dating back to their birth. In 2006, there was a big uproar over a now-central feature of Facebook, the news feed that tells people what their friends are doing.