And what link would that be. Your first link said they were "sent home", but your second one lists that the vast majority of those were "voluntary departures", which, as I understand it, means that the INS makes them sign a statement saying that they'll leave, and then TURNS THEM LOOSE, only taking their word that they have actually left. Until someone turns up PROOF that they are REALLY GONE, then I put that "six million" down as a fantasy.
Oh, and by the way, if that "6 million" turns out the be real, it demolishes your argment that we can't deport them successfully. If we can deport 6 million, we can certainl deport 12 million (or even 18 million).