The email was written by K.T. McFarland, who at the time had been tapped to serve as deputy national security adviser and has now been nominated to be the U.S. ambassador to Singapore. In the Dec. 29 email, which was described to The Washington Post by two people who have seen it, McFarland characterized new sanctions imposed against Russia by President Barack Obama as an attack against the legitimacy of Trump's election that could hurt Trump's efforts to work with Russia.