We just got off the phone with Andrew Bosworth, Facebook's Director of Engineering, who sought to clear up some of the confusion recently about the company's decision to hide all email addresses besides @facebook.com email addresses from user profiles. The press reported today that as a result of these changes, only @facebook.com were getting pushed to users' mobile phones and stranding them without vital contact information.

While Facebook did intend to make your @facebook.com email address the only visible email address on your profile, it didn't intend for this to be the only email address that gets synced to friends' phones. Bosworth stressed that "visibility settings" are a lot different from "privacy settings," and that this misunderstanding too needs to get sorted out — but neither of these things affect a contact sync API bug that coincidentally just reared its head.

Privacy_visiblity

Last week, Facebook let you decide which of your email addresses you want to be visible on your profile. Since the visibility settings toggle (on/off) is a new one, the company decided to start people off with "invisible" by default. This doesn't change the fact that people can still search for these invisible email addresses and find you — they just won't show up on your profile. If you change privacy settings for any email address to "Nobody," nobody will be able to ever see that email address. Facebook may've made a mistake with the decision to hide a person's email addresses by default, but on the whole, having two toggles (one for profile visibility, one for privacy) will be valuable for users in the long run. What got people more riled up were the alleged repercussions of this decision.

As the echo chamber reached a fever pitch about hidden email addresses, Android, Blackberry, and iOS 6 beta users realized that their phones were syncing only @facebook.com email addresses. As a result, users who had relied on Facebook for email addresses found themselves unable to contact friends. While the two situations appear related, the reason for the erroneous syncing is a bug that only syncs the most recently added email address to users instead of an account's primary email address. Since Facebook recently added @facebook.com email addresses to every account, these have been the sole email addresses that have been synced.

An apologetic Bosworth said the bug would be fixed tomorrow, if not sooner. The company elaborated, in a statement just now:

Contact synchronization on devices is performed through an API. For most devices, we've verified that the API is working correctly and pulling the primary email address associated with the users' Facebook account. However, for people on certain devices, a bug meant that the device was pulling the last email address added to the account rather than the primary email address, resulting in @facebook.com addresses being pulled. We are in the process of fixing this issue and it will be resolved soon. After that, those specific devices should pull the correct addresses.

Once the contact sync API bug has been fixed, you should start to see friends' "primary" email addresses show back up on your devices. This, however, does not change the fact that the only "visible" email address on your profile will still be just your @facebook.com address — unless you hop into your profile settings and unhide your other email addresses, that is.