Fatwa No. 114836 on Islamqa.info
Fatwa No. 114836, published undated on Islamqa.net, asked, "What is the ruling of shari'a on email hacking? Is it permissible to hack emails which belong to Jews and infidels?" The answer given was that it is prohibited to hack people's emails, as shari'a prohibits violation of people's privacy. The sheikh issuing the fatwa listed several exceptions to this rule, one of which is that in time of war between Muslims and others, it is permissible to hack emails to obtain information about the enemy, their number, their location, and their weapons.
May 8, 2013