Calling them private is certainly technically correct (the best kind of correct), but the term is sufficiently overloaded that I thought it would be worth point

Calling them private is certainly technically correct (the best kind of correct), but the term is sufficiently overloaded that I thought it would be worth pointing out that they don't seem to contain personal information (e.g. people talking about their children or their marriage trouble). I don't think that this is the result of someone reading all their emails and releasing the ones without personal information (which I don't think would be okay, I'm not sure how you got that impression), but a result of everyone using @scientology.co.at email addresses. As I said above, I do not think that the lack of personal information by itself makes releasing them okay, but I do think that the combination of the CoS being secretive and "evil" gives this particular hack some (moral, not legal) legitimacy, because it is difficult to get this information using less dodgy methods.