As I understand it, when an email address on Facebook gets synced to a phone, that's just a cache. Any updates to the email address on Facebook automatically update the cache. When friends update their email addresses, the cache gets overwritten and you don't have their old addresses anymore.
But now, Facebook changed people's email addresses without their permission. The cache gets updated, and boom, the old address is gone.
But what makes it more scary is that people don't actually remember that they originally got the address from Facebook and they don't understand the caching behavior. All they know is that the old address is gone. So they think that email addresses that they didn't get from Facebook are also at risk.
The workaround is to manually copy email addresses from Facebook to some other system. Any email addresses you get from Facebook by automatically syncing aren't safe.
It's a pity; after all, most of the point of the system is that you shouldn't have to manually update your address book when your friends change their contact info.
That's an excellent explanation. It also fits the mold of just about every other "service X broke into service Y and stole my info" story, wherein people forget lots of other plausible explanations.
And a good lesson as to why you should never make unannounced changes to your user's data. They will think you "broke" something, even if it never worked the way they thought it did.
But now, Facebook changed people's email addresses without their permission. The cache gets updated, and boom, the old address is gone.
But what makes it more scary is that people don't actually remember that they originally got the address from Facebook and they don't understand the caching behavior. All they know is that the old address is gone. So they think that email addresses that they didn't get from Facebook are also at risk.
The workaround is to manually copy email addresses from Facebook to some other system. Any email addresses you get from Facebook by automatically syncing aren't safe.
It's a pity; after all, most of the point of the system is that you shouldn't have to manually update your address book when your friends change their contact info.