RFC 7489, "Domain-based Message Authentication, Reporting, and Conformance (DMARC)", March 2015Source of RFC: INDEPENDENT
Errata ID: 5552
Reported By: Borislav Petrov
Date Reported: 2018-11-09
Section 10.3. says:
Everything about it..
DMARC relies on inspecting header information. This section suggestion is not allowed by rfc5321 and contradicts it:
...a relay SMTP has no need to inspect or
act upon the header section or body of the message data and MUST NOT
do so except to add its own "Received:" header field..
So the correct behaviour shoud be only the second option - 2xy and decide what to do after that being silent or not.