Project Honeypot:

Project Honey Pot is a web-based honeypot network. It uses software embedded in websites. It collects information about the IP addresses used in the collection of email addresses in spam, bulk mail and other fraudulent email.

Internet.nl:

Here you can test the security of websites yourself. This test is developed by SIDN (Stichting Internet Domeinregistratie Nederland) in cooperation with the Dutch government and is especially useful for website builders and marketing personnel.

MX toolbox:

A useful website for system administrators, administrators of DNS and email systems, and of course for other interested parties. There are dozens of free tests to do, especially for email servers.

Scamadviser:

A similar website to Fraud Detector, however, mainly focused on the American market and on American websites. For European websites, Scamadviser is less suitable at this time.

Have I been powned:

A very useful website where you can check for yourself if your email address has been involved in a hack.