Is it possible that Facebook actually doesn't deliver your private message to a friend? As in, it's in your sent messages, and you see it as sent in the message thread with that friend, but the friend claims that they never received it, and shows you the same message thread from their Facebook account without that message in it? Basically, does that mean that the friend either deliberately (which is more likely) or accidentally deleted your message, or is it actually possible that Facebook made a mistake and didn't really deliver the message in question to your friend?
I'd especially like to know if it's possible for a mistake like that to happen more than once in a short period of time.
@facebook), but the email address of your user (e.g.@yahooor@gmailor whatever). – Alex Jun 7 '12 at 10:19