DMARC Record

DMARC (Domain-based Message Authentication, Reporting and Conformance) is a mechanism that allows to the e-mail senders and receivers to determine or not a given message is legitimately from the sender, and what to do if it isn’t. The DMARC record allows easier to identify spam and/or phishing messages, received in the Customers's mailbox, and to keep them out of there.

Example of DMARC record:

Host	Type	Points to:	TTL
_dmarc.yourdomain.com	TXT	v=DMARC1;p=reject;pct=100;rua=mailto:mailmaster@postmaster.com	3600

In the example shown above, the sender requests that the receiver outright reject all non-aligned messages and send a report, in a specified aggregate format, about the rejections to a specified address. If the sender was testing its configuration, it could replace “reject” with “quarantine” which would tell the receiver they shouldn’t necessarily reject the message, but consider quarantining it.
DMARC records follow the extensible “tag-value” syntax for DNS-based key records defined in DKIM.

You can see the available tags here:

Tag name	Purpose	Sample
v	Protocol version	v=DMARC1
pct	Percentage of messages subjected to filtering	pct=20
ruf	Reporting URI for forensic reports	ruf=mailto:authfail@example.com
rua	Reporting URI of aggregate reports	rua=mailto:aggrep@example.com
p	Policy for organizational domain	p=quarantine
sp	Policy for subdomains of the OD	sp=reject
adkim	Alignment mode for DKIM	adkim=s
aspf	Alignment mode for SPF	aspf=r

To add DMARC, you need to create a TXT record in your DNS Zone. You can see the example below:

Wiki

DMARC Record