Checking if an email address is in a data breach and checking the user can click an activation link is a good way to de-spam free services.
Most real humans have at least one address involved in a data breach, but most don't have access to hundreds of emails in a data breach. That means most people can only make use of the "one free ice cream per customer" deal once.
Most real humans have at least one address involved in a data breach, but most don't have access to hundreds of emails in a data breach. That means most people can only make use of the "one free ice cream per customer" deal once.
Pretty neat!