Fight Spam—Reject Cases Without reCAPTCHA Verification
Where: This change applies to Salesforce Classic and Lightning Experience in Essentials, Professional, Enterprise, Performance, Unlimited, and Developer editions.
How: In Setup, go to the Web-to-Case Settings page, and look for the Require reCAPTCHA Verification setting. Enabling this setting turns on the Include reCAPTCHA in HTML setting on the Web-to-Case HTML Generator page. Then make sure that the HTML on your website includes the reCAPTCHA code.
In new orgs, Require reCAPTCHA Verification is enabled by default.