Domain-Based Message Authentication (DMARC) Explained

DMARC or and domain-based Message Authentication, Reporting, and Conference, DMARC is a technical standard that helps protect email senders and recipients from spam, spoofing and phishing. DMARC permits an organization to bring out a policy that defines its email authentication practices and gives instructions to receiving email servers for how to enforce them. In this article, we will explain to you what is DMARC and how it works.

DMARC is a method for a domain owner to the following:

  • To bring out its email authentication practices.
  • To state what actions should be taken on mail that fails authentication checks.
  • To facilitate reporting of these actions taken on mail claiming to be from its domain.

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What Is A DMARC Report?

DMARC reports are generated by the inbound mail servers as part of the DMARC validation process. There are usually two formats of DMARC reports:

  • Aggregate reports: they are XML documents showing the statistical data about the messages received that claim to be from a particular domain. The data reported includes authentication results and message disposition. Aggregate reports are created to be machine-readable.
    • They are sent on a daily basis.
    • They provide an overview of the email traffic.
    • They Include all the IP addresses that have tried to transfer the email to a receiver using your domain name.
  • Forensic reports: They are the separate copies of the messages which failed authentication, each enclosed in a full email message using a special format called AFRF. Forensic reports can be beneficial both for troubleshooting a domain’s own authentication issues and for identifying malicious domains and websites.
    • They are Real-time
    • They are only sent for failures
    • They Include original message headers
    • They may include original messages.

Why Use The DMARC?

The main objective of the DMARC is to detect and prevent email spoofing. If you have a business sending commercial or transactional email, you definitely need to implement one or more forms of email authentication to verify that an email is actually from you or your business.

Configuring DMARC to assist in receiving mail servers determines how to analyze messages that claim to be from your domain, and it is one of the most important steps you can take to improve your deliverability. However, standard life DMARC only goes so far; email experts suggest implementing a DMARC email authentication policy in the context of a complete messaging strategy.

For example, you may have received messages from the bank that your card is not valid anymore and you need to provide some details to reactivate. But these are actually spam emails that are sent using the domains from the banks. You are not able to identify if they are real or spam. So, DMARC helps you prevent email spoofing.

Earlier, the email authentication techniques DKIM and SPF helped to protect your domains from scams like this. But cybercriminals found ways to bypass the security measures. To fully secure your domain, DMARC creates the link between the SPF and DKIM.

Ways To Reduce The Impact Of The Spoofing With DMARC

There are possible ways that instruct the email receivers what to do with an email that fails the DMARC checks. In the DMARC record, a DMARC policy instructs an ISP how to handle emails that fail the DMARC checks. Email receivers check if the incoming messages have the valid SPF and DKIM records and if they align with the sender’s domain. A message can be considered as DMARC compliant or DMARC failed only after these checks.

There Are Three DMARC Policies Available

  • Monitor policy (p=none): monitor policy takes into consideration the email the same as it would be without any DMARC validation. It does not create any impact. It remains intact.
  • Quarantine: This policy accepts the mail but puts it somewhere other than the recipient’s inbox (typically the spam folder).
  • Reject: As its name suggests, the reject policy rejects the message outright

Keep in mind that the DMARC policy instructs to handle the email as per the DMARC policy. But, the email receivers are not obliged to take the DMARC policy into the account. The email receiver has his own policy that they use sometimes.

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