Whether you've noticed or not, you have a new primary email address listed as your Facebook contact and most likely, it's an address you've never used.

The social-networking site has quietly replaced your default email addresses such as Gmail and Yahoo! with your @Facebook.com address, an email service option the company launched a few years ago and synced with Timeline in April.

"As we announced back in April, we’ve been updating addresses on Facebook to make them consistent across our site," a Facebook spokesperson told Mashable. "In addition to everyone receiving an address, we’re also rolling out a new setting that gives people the choice to decide which addresses they want to show on their Timelines."

First spotted on Saturday by blogger Gervase Markham, the email address you once listed as your point of contact is now hidden in the site's database and your assigned @Facebook.com address is highlighted for friends to see.

If you ever changed your Facebook vanity URL, that serves as the prefix of your Facebook email address (i.e. Facebook.com/John.Smith would be John.Smith@Facebook.com). For those that never added a vanity URL, Facebook has assigned numbers to serve as your email account name.

When users send an email to your Facebook.com address, it pops up in your Facebook inbox. However, some users have experienced issues with receiving messages through Facebook, since some of them end up in an "Other Messages" folder that few people know about.

Although members have been slow to embrace their Facebook email address, the move may be a part of an effort to remind and encourage users to use it more.

If you want to switch your email contact information back to what it was, it's easy to do. Visit your Timeline or profile page and select "About" under your contact information. You can then hide your Facebook email address from the contact page and elect to highlight another email address.

"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," the Facebook spokesperson added.

What do you think of your Facebook email address? Will you use it? Let us know your thoughts in the comments.