What is DMARC?

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is a standard that prevents spammers from using your domain to send email without your permission — also known as spoofing. If you are new to email authentication, we recommend first reading about DKIM and SPF. In combination with SPF and DKIM, a DMARC policy in DNS allows you to set rules to reject or quarantine emails from sources you do not know or trust. As part of the DMARC spec, ISPs (Gmail, Yahoo, Microsoft and more) who implement DMARC will also generate reports on sending activity for your domain. For further reading, check out Postmark’s guide on DMARC.

What do these tags mean on my DMARC DNS Record?

Tag Description Example
v Protocol version v=DMARC1
p Policy for organizational domain p=none
pct Percentage of messages subjected to filtering pct=100
rua Reporting URI of aggregate reports rua=mailto:name@domain.com
sp Policy for sub-domains of the organizational domain sp=none
aspf Alignment mode for SPF aspf=r
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