You might not know this, but you have a Facebook email address. It’s [yourusername]@facebook.com. The thing about it is that it unifies SMS messages, instant messages and emails in a single system: The Facebook Message. It was at one point called a Gmail killer. As you might guess, it has not killed Gmail, or email or mail mail. But in the last day or so, Facebook’s begun making a subtle switch to the contact info listed on your profile: In a change that’s rolling out gradually, your Facebook email is now the default address shown, even though you’ve probably never told somebody to send an email to your Facebook account.

The official explanation for the change, a Facebook spokesperson told us, is this:

As we announced back in April, we’ve been updating addresses on Facebook to make them consistent across our site.

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.

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.

Obviously, though, more people are now going to send emails to Facebook addresses, since that’s the one that’ll show up on your profile. Whether or not that’s the sole intent, it doesn’t make the change necessarily nefarious: Facebook messages are now a buffer between people you might not want emailing you and your real inbox. (Though if you really really didn’t want people emailing you, I suppose you shouldn’t have listed your address on Facebook in the first place. Or you could jump off the internet and die.)

The more subtle effect, the more direct collapsing of the medium of email into a medium-agnostic bucket of messages, is perhaps more profound. “Email is broken” is a refrain that never dies, it merely dozes. (Along with SMS “is too expensive.” Less common but perhaps truer is that IM is “convoluted.”) But what if you just have a giant bucket of messages? Some are “emails,” some are “texts,” some are “IMs,” but they all look and feel the same. Suddenly the form of email, and every other kind of message, is very formless. They’re all just another group of words in a stream. The only difference between an email address and your IM name or phone number is the format, a tiny icon in the corner denoting where it came from. It all goes to one place.

Facebook is now explicitly telling the world to use this unified stream of words as email. And maybe that’s how we fix all of those things — broken email, expensive texts, convoluted instant messages — by putting them all into a juicer and hoping what comes out is better than any of them alone. Or maybe it’ll just make an even bigger mess.