And regardng Rabbeinu Gershom’s ban. The way I heard it, he had two wives, one old and one young. The young one pulled out all his gray hairs so he would look young, and the old one pulled out all his black hairs so he would look old, leaving the poor man completely bald and beardless. In other words, if you want peace in your home, stick with the wife of your youth.
Not reading other people’s mail and knocking before entering are just common courtesy, and that he had to codify them in a ban probably just means that people in his time were getting lax about some aspects of derech eretz.
It’s interesting to me to note that many aspects of “Western sensibility” were actually influenced by Jewish values, and our discomfort with them actually stems from our having been influenced by the talk-radio lack of courtesy and glorification of toughness and force that has leaked into our camp. Perhaps we should try to emulate R’ Yaakov in gentleness and courtesy, rather than talk-radio guys who always have the perfect insult.