Evan Brown at Internet Cases has a good writeup of Steinbach v. Village of Forest Park, No. 06-4215, 2009 WL 2605283 (N.D. Ill. Aug. 25, 2009) which holds that email snooping can be a tortious intrusion upon seclusion.
My e-home is my (cyber) castle.
I can agree that my own e-home is my cyber castle, because in my e-mail there is some very private info which I prefer to keep secure. And e-mail snooping can be a threat to my private world. However, different people have various nterpretations about what is private information.