Microsoft will notify its Hotmail users (so will Yahoo! users, see article link at the end) about hacks that are state-sponsored. As the article explains, state-sponsored hacks usually lasts for a prolonged period of time, and are potentially more dangerous than by criminal hackers.
In addition, Microsoft is pointing at Chinese agencies doing the hacking, which target Uighurs and Tibetans, because the Chinese government’s belief in these groups as serious trouble-makers. The U.S. government has also accused China of putting a significant portion of state workers’ private info. in jeopardy, but Pres. Xi has denied those attacks when Pres. Obama and Xi met in Sept. 2015.
The article below is copied and pasted from The Guardian.