I am sooooooo glad to see you are putting this back in. The idea of creating a public notebook was by virtue of that choice, NOT intended to be secure. warn me again before I agree.. but please let's hope this stays as a feature in future releases. I didn't use it often, but a public notebook URL is NOT the same as adding more email addresses. (in most cases, I won't know who is linking to my public notebook that I want open).