A receiver can override the policy that is set in your DMARC record.

One such example is when you have set a reject policy (p=reject) and the email that you send goes through a mailing-list that fails both SPF and DKIM. In such a case, DMARC will fail, however, the receiver can override your policy and accept the email. Some of the common DMARC overrides are explained below:

forwarded:  Message was relayed through a known forwarder, or local heuristics has identified this message as likely having been forwarded. There is no expectation that the authentication would pass.

local_policy:  The Mail Receiver’s local policy has exempted the message from being subjected to the domain owner’s requested policy action.

mailing_list:  Local heuristics determined that the message has arrived through a mailing list, and therefore the authentication of the original message was not likely to succeed.

other:  Some policy exception that was not covered by other entries in this list has occurred.  Additional details can be found in the “comment” field of PolicyOverrideReason.

sampled_out:  Message was exempted from the application of policy by “pct” setting in DMARC policy record.

trusted_forwarder:  Message authentication failure was expected by other evidence that linked the message to a locally-maintained list of the known as well as trusted forwarders.