Open Relay Checker v2 - Test open relay servers and get a list of pub

This testing tool allows users to scan and check their open relay servers. It tests smtp relays, blind anonymous relays and public proxy lists also. Used by some people at abuse.net and sendmail.org to test open relays.

Site Features include:

Open Relay Database
Open Relay Usage Articles
FAQs and How-tos
Closing Relays and Protecting your Mail Server
Anti Spam Tips
Public SMTP List
Server list updated daily

The software is free but it costs $29 per month to join their site.