Clarification on Clay Credit Usage for Email Enrichment

Hey, Clay. I cannot get one thing, if the email provider that is connected with clay doesnt find proper email for the person, will it charge a clay credit or not? I mean, if I buy a subs with 3000 credits and then try to enrich 3000 people with emails will I be charger for 3000 credits? or only for 1000 emails that were found? for instance