The email address shown in the actual blog post isn't a very good advert for either privacy or Mailbox.org.
If a person is so concerned about privacy why do they let the whole world see their actual email address on their blog page?
Running that email address via
https://email-checker.net/ provides a Bad result which when checked further using
https://check.spamhaus.org/results/?...92ff:feeb:f508 shows that the actual email address is either misconfigured, or insecure, compromised, or infected