To monitor your security posture, view whether the Allow redirections to untrusted external URLs without warning setting is enabled in Health Check.
Where: This change applies to Enterprise, Performance, Unlimited, and Developer editions.
How: From Setup, in the Quick Find box, enter Health Check, and scroll to Informational Security Settings. Then view the Allow redirections to untrusted external URLs without warning setting status.
Evaluate URL Redirection Setting in Health Check (salesforce.com)