How to check if Lead Email already exists in Account or Contacts

After attending a trade show we have the list of all the people who allowed us to scan their badges. Our normal routine is to upload them all as leads until they are qualified. Is there a way we can check if their email domain already exist in contacts?

Moderation update: I am locking this post to avoid redundancy. We will retain the post as the parent post.
Link to parent post: https://help.zoho.com/portal/en/community/topic/crm-duplicate-email-check-between-leads-and-contacts-module