First, Moderators are assigned in forums. They moderate posts, move them, edit them, etc. When someone posts a new post, they should receive an email, as long as their profile preferences are not disabling mail.
User-levels let the system know, through Joomla and other extensions by way of Joomla user-levels, what content can be published, edited, etc. Content is articles, not forum posts.
I think this is where the confusion lies?