Links
- https://eml-analyzer.herokuapp.com/#/
- https://email-security-scans.org/
- https://spameatingmonkey.com/
- https://cybersecurity.opentext.com/products/email-security/email-encryption/
- https://greathorn.com
- https://spamassassin.apache.org/gtube/
- https://mxtoolbox.com/emailhealth
- https://www.learndmarc.com/
- https://en.wikipedia.org/wiki/Hashcash