The intent of all the rules is to keep the QB a good place to be on, and while I am sometimes frustrated with some of the interpretation of the rules, I respect the rights of admin to ultimately decide what is allowable.
Anyone who isn't willing to accept this can always exercise their rights to go elsewhere.
I also can attest to what quiltingcandy says in that no email is going to be totally private when you are communicating through a public forum, even from the private message part of it.