Companies that engage in business to business services.

Say you have a free demo of the product you’re selling, but you want to limit downloads to other legitimate businesses, because that’s your market.

You gate it behind a form, and rig the form submission to reject free and ISP email addresses.

So [email protected] - desirable and allowed. [email protected] or cox.net - not your market, block form submission.

Happens ALL the time.