The quote includes going through you csv file (export from excel as csv), then making checks whether email field is in email format (@domain, no illegal charexters, etc).
Script woykd produce the same csv format, but with extta column 'valid' yes/no.
if you want to actually check whether the email is live and emails can reach it, then we will need to use one of the paid services api (quote will be 180$ then). we should discuss it furtger in details then