Domain-based Message Authentication, Reporting, and Conformance (DMARC) monitor email messages using Sender Policy Framework (SPF), and Domain Keys Identified Mail (DKIM).

The Domain-based Message Authentication records facilitate the interception of malicious email practices, such as domain spoofing to phish for personal information, by Internet Service Providers (ISPs). DMARC protects from email compromise, phishing, and spoofing for both large and small domain owners.

How DMARC Works?

To meet DMARC’s requirements, an email domain must also have SPF or DKIM. A Domain-based Message Authentication record must be published in the DNS to deploy DMARC.

In a DNS record, a Domain-based Message Authentication entry tells the world your email domain’s policy after it has checked its SPF and DKIM status.

Both SPF and DKIM must be passed for Domain-based Message Authentication authentication. Alignments like these are known as DMARC alignments. The identifier alignment for SPF and DKIM passes, but DMARC might fail.

In addition to being able to identify email servers, Domain-based Message Authentication records can also be used to send XML reports to reporting email addresses. In addition to providing information on your email’s migration, these reports also help you identify everything that is using your email domain. It can be difficult to understand reports written in XML due to their size and complexity.

Why Use DMARC for Email?

The email channel has a wider reach than any other channel with almost 5 billion accounts worldwide. Consequently, this channel is used for malicious purposes by cybercriminals. The crime rate on this channel, however, has continued to increase despite improved security measures in recent years. Email accounts for more than 95 percent of all hacking attacks.

Domain-based Message Authentication adds valuable information about domains. It doesn’t only give full insight into email channels but also makes phishing attacks visible. DMARC can also mitigate the impact of these attacks. Benefits of DMARC

Domain-based Message Authentication can be implemented for the following reasons:

  • Reputation: When you publish a domain-based Message Authentication record, you protect your brand from unauthenticated parties. DMARC records can sometimes boost the reputation of a domain simply by being published.
  • Visibility: By providing you with information about who is sending emails from your domain, Domain-based Message Authentication reports give you greater insight into your email program.
  • Security: By establishing a consistent policy for handling non-authenticated emails, Domain-based Message Authentication empowers the email community.

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Misunderstandings about DMARC

  1. DMARC is a magnified spam filter
    Domain-based Message Authentication is relatively new; first published in early 2012, with the main goal purpose of protecting users from being impersonated over email communication.
  1. There’s no point implementing DMARC if some receivers are not checking
    Most people have wondered what if the receiver is not validating the Domain-based Message Authentication record, which will still leave them vulnerable to attacks; however, that is not the case.
  1. DMARC will affect my legitimate email deliverability
    Domain-based Message Authentication has a monitoring mode, which has no impact on the email flow.
  1. It is easy to deploy DMARC 
    Domain-based Message Authentication reports can be complicated to parse and difficult to correlate sending IP addresses.
  1. DMARC prevents every email attack
    If your domain is compromised, Domain-based Message Authentication will not protect you. To avoid phishing emails from reaching your inbox, you need additional protection in all three cases described above.

DMARC Best Practices and Tools

  • Begin by monitoring the impact: For big businesses setting up Domain-based Message Authentication on various domains, start with a simple monitoring-mode record that has its policy set to p=none.
  • Plan to use SPF and DKIM: Remember that Domain-based Message Authentication won’t work unless all legitimate sources of email are certified using SPF and DKIM.
  • Quarantine emails that fail DMARC on external systems: Domain-based Message Authentication can be implemented as soon as you believe that SPF, DKIM, and most of your legitimate traffic are protected.
  • DMARC-failing messages should not be accepted by external mail systems: Your final step is to implement the reject policy once your mail has been fully authenticated. A secure domain is the final and best way to prevent unauthorized emails from reaching your clients.

DMARC Examples

  • Protocol version (v)
  • Percentage of messages subjected to filtering (pct)
  • Reporting URL for forensic reports (ruf)
  • Reporting URL of aggregate reports (rua)
  • Policy for an organizational domain (p)
  • Policy for subdomains of the OD (sp)
  • Alignment mode for DKIM (adkim)
  • Alignment mode for SPF (aspf)

Final Thoughts

Despite the rapid adoption of these technologies, the problem of deceptive and fraudulent emails has not subsided. By employing these technologies, email receivers seem to be able to determine genuine from fake emails, if they use these technologies. Several reasons have prevented that from happening.