As for any claim that DMARC 'extends' SMTP or DNS, it's difficult to
imagine the technical logic behind such an assertion.
The argument that it extends SMTP is not totally ridiculous. Where
did these SMTP rejections come from, if not DMARC?
2014-04-07 08:18:59.693287500 delivery 117461: failure:
2607:f8b0:4001:0c03:0000:0000:0000:001b_failed_after_I_sent_the_message./Remote_host_said:_550-5.7.1_Unauthenticated_email_from_yahoo.com_is_not_accepted_due_to_domain's/550-5.7.1_DMARC_policy._Please_contact_administrator_of_yahoo.com_domain_if/550-5.7.1_this_was_a_legitimate_mail._Please_visit/550-5.7.1__http://support.google.com/mail/answer/2451690_to_learn_about_DMARC/550_5.7.1_initiative._k7si18580912icu.45_-_gsmtp/
2014-04-07 08:19:00.680001500 delivery 117452: failure:
2607:f8b0:4001:0c03:0000:0000:0000:001b_failed_after_I_sent_the_message./Remote_host_said:_550-5.7.1_Unauthenticated_email_from_yahoo.com_is_not_accepted_due_to_domain's/550-5.7.1_DMARC_policy._Please_contact_administrator_of_yahoo.com_domain_if/550-5.7.1_this_was_a_legitimate_mail._Please_visit/550-5.7.1__http://support.google.com/mail/answer/2451690_to_learn_about_DMARC/550_5.7.1_initiative._c1si22721698igj.35_-_gsmtp/
R's,
John