I believe the "(2015)" label is intended for articles from 2015. This article is from 2018, but its contents reference 2015. Perhaps a better title would be "

I believe the "(2015)" label is intended for articles from 2015. This article is from 2018, but its contents reference 2015. Perhaps a better title would be "Leaked email shows how Cambridge Analytica and Facebook first responded in 2015".