Understanding DMARC and Its Functionality

Understanding DMARC and Its Functionality 1

What is DMARC?

DMARC stands for Domain-based Message Authentication, Reporting & Conformance. It is a security protocol designed to protect email domains from being used for email fraud, phishing scams, and other cybercrimes. DMARC leverages on two existing email authentication technologies – Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) – to provide email domain owners with greater control over their email channel, which leads to better protection against fraudulent activities. Utilize this external content to explore the subject further. https://www.tangent.com/solutions/security-compliance/dmarc, broaden your understanding of the covered topic.

Understanding DMARC and Its Functionality 2

How does DMARC work?

The core function of DMARC is to authenticate an email sender’s identity claim, and specify how a receiver should handle messages that don’t pass authentication. DMARC uses SPF and DKIM to authenticate emails, and it requires the sender domain to both have and publish SPF and DKIM policies.

SPF validates the IP addresses of incoming messages against the list of authorized IP addresses of a sender domain. DKIM, on the other hand, uses digital signatures to authenticate the identity of the sender using a private/public key pair. DMARC then combines the result from both SPF and DKIM, specifies the action to be taken if the message does not pass DKIM or SPF authentication checks and sends an email report to the domain’s owner, providing detailed information on how messages from the domain are being treated by receivers.

In summary, DMARC helps email receivers identify and reject fraudulent emails by checking if the email is coming from an authorized IP address and checking the validity of the sender’s digital signature. If an email fails DMARC checks, the receiver takes appropriate actions based on the DMARC policy defined by the sender, including rejecting or quarantining the email.

Why is DMARC important?

DMARC is essential because spammers use legitimate email domains to send unsolicited emails, putting both senders and receivers at risk of email fraud, phishing, and other scams. It ensures that email messages are only sent by genuine domain owners, increasing email authentication, and strengthening sender reputation. DMARC also prevents spoofing of email addresses by ensuring emails are sent from authorized machines and authenticated sources.

Moreover, DMARC provides valuable insights that help organizations protect their brand reputation. Since DMARC generates reports of suspicious activity, domain owners can quickly identify and shut down sources of fraudulent activity by using the reporting information to quarantine or reject suspicious emails.

How to Implement DMARC?

DMARC implementation begins by publishing SPF and DKIM records for your domain in the DNS configuration as both technologies are prerequisites for DMARC. Once SPF and DKIM are in place, the domain owner sets a DMARC policy that outlines how receivers should handle emails that fail DMARC tests. The options include ‘none,’ ‘quarantine,’ or ‘reject,’ depending on how strict the policy is. A DMARC record is then published in a DNS TXT record, containing the details of the policy and where the email report should be sent if necessary.

Importantly, DMARC implementation should be gradual, as setting a too strict policy could result in a higher rate of false-positives and block legitimate emails. It’s advisable to set the policy to ‘none’ initially, allowing time to monitor the incoming emails and understand how the organization’s email environment operates. When you’re confident of the email sources and know what to expect, you can then start to increase the level of strictness.


DMARC is a powerful security protocol that can protect an organization’s email channel from fraudulent activities, phishing scams, and other email-based threats. It requires the sender domain to publish valid SPF and DKIM policies, which will authenticate emails, and the policy definition to use DMARC explicitly. With DMARC, domain owners can enhance email security, improve authenticity, and reduce email fraud. Learn more about the subject by visiting this carefully selected external resource. https://www.tangent.com/solutions/security-compliance/dmarc, unveil worthwhile knowledge and fresh viewpoints on the subject addressed in the piece.

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