I have a couple questions I am filing in the general

I have a couple questions
I am filing in the general setting information
and I am a little confused with this question
Yes, members will get confirmation email to subscribe to newsletters (only for not registered users)

if they are not a registered user how do they get in the list?

I am needing to have all registered users confirm they want to receive
my newsletter before they will receive the news letter how can I do this?

I am on a hosting account that has a zero tolerance for spam
if some one reports me for spam I need to be able to prove the
opted in to my news letter how can I prove this
and I need to be able to prove that if some one reports me for spam