service/email.md

@@ -375,6 +375,8 @@ Those services also provide ways to validate SPF records:
  * <https://www.kitterman.com/spf/validate.html> - by a Debian
    developer
  * [pyspf](https://pypi.org/project/pyspf/): a Python library and binary to test SPF records
+ * [learndmarc.com](https://www.learndmarc.com/): has a Matrix (the movie) vibe and more
+   explanations
 
 ### Testing the submission server