Email Scraping

Does email scraping means just extracting all the emails that are on the site (for example someone may leave his email in a post -someone may leave it as a signature but it's available )? or it does mean also extracting all the emails including the emails that people used to register in the site?

scraping mean only to extract the visible email on the page or in the page source code

not possible to get the email people use to signup, that is hacking