According to this article on CNET,
A court in Australia has ruled that lawyers foreclosing on a couple’s home can serve them with legal documents through Facebook. The purpose of the suit: to let a couple know that they’re about to lose their home through foreclosure after defaulting on a loan. Legal experts say U.S. law isn’t far behind.
US courts have allowed the notices to be delivered through email. Not sure how many of them will get back by saying “We never received it”