It doesn't sound like rationalization, to me it sounds like you are expressing your well-thought out ideas.

Regarding your boss, I can tell you as someone who is in management, I've been told when people email us their notice, we are not to respond, we are to wait for them to come to us (which I can't do, I don't think it's right). If this isn't someone you see daily, you may want to place a phone call just as a follow up. Good luck!