- Learn and Test DMARC[1] does a visual breakdown of how email servers communicate, giving you a better understanding of SPF, DKIM, and DMARC and how they work together.
- Mail-Tester[2] - test the spammyness of your emails.
- MECSA[3] is an online tool developed by the Joint Research Centre (JRC)[4] to assess the security of email communication between providers.