The ESPC's Sender ID testing tool simply requires the sender to send an email using the domain they are testing, then with a single click, a report on the email is returned with information showing whether SPF and Sender ID validates properly. The system can also help test that Sender ID records properly reject "spoofing" domains commonly used in "phishing" attacks. Contributed by ESPC steering committee member SKYLIST, the authentication testing tool is open to the general public.