Mail.ru Group is controlled by Alisher Usmanov, an oligarch from the 90s and an old friend of Putin. Few years back Mail.ru group with the help of russian secret services staged a hostile takeover of VK, biggest social network in russia, essentially forcing the founder to leave the country. Since then VK data has been freely available to any russian enforcement agency, or even anyone pretending to be one. In russia there isn't even a pretense of privacy/independence from them, everyone knows FSB&Friends have unrestricted access to their stuff