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Understanding DMARC Check Results And Improving Email Deliverability

Jun 4

Email communication is a cornerstone of modern business operations, yet it is constantly threatened by phishing, spoofing, and other malicious activities. Domain-based Message Authentication, Reporting & Conformance (DMARC) is a protocol designed to combat these threats. Understanding DMARC check results and taking steps to improve email deliverability are crucial for ensuring that legitimate emails reach their intended recipients while unauthorized ones are blocked.


What is DMARC?


DMARC is an email authentication protocol that works in conjunction with SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail). It enables domain owners to specify how an email from their domain should be handled if it fails authentication checks. By providing a way for email receivers to report back on messages that pass or fail DMARC evaluation, it offers valuable insights into potential abuse and deliverability issues.


Importance of DMARC Check Results


DMARC check results play a pivotal role in protecting email domains from being used in phishing and spoofing attacks. They help domain owners:


  • Identify unauthorized uses of their email domains.
  • Gain insights into legitimate email sources.
  • Enhance email deliverability by ensuring only authenticated emails reach recipients.


Components of DMARC Check Results



DMARC check results include several key components that provide detailed information about the authentication status of emails. These components are:


SPF Alignment


SPF alignment checks if the sender's IP address is authorized to send emails on behalf of the domain. A positive SPF alignment indicates that the email is likely from a legitimate source, whereas a negative result suggests potential spoofing.


DKIM Alignment


DKIM alignment verifies that the email has not been altered during transit by checking the DKIM signature against the domain's public key. If the DKIM signature aligns with the sending domain, it confirms the email's integrity and authenticity.


DMARC Policy


The DMARC policy dictates the action to be taken when an email fails both SPF and DKIM checks. The policies can be:


  • None: No specific action is taken, but reports are generated.
  • Quarantine: Emails failing DMARC checks are sent to the spam/junk folder.
  • Reject: Emails failing DMARC checks are not delivered to the recipient's inbox.


Interpreting DMARC Reports


DMARC reports, also known as aggregate and forensic reports, provide detailed feedback on email authentication results.


Aggregate Reports


Aggregate reports offer a summary of DMARC evaluation results over a period of time. They include data on the number of emails passing or failing DMARC checks, providing insights into overall email authentication performance.


Forensic Reports


Forensic reports offer detailed information on individual email messages that fail DMARC checks. These reports help in identifying specific issues with email authentication, such as incorrect SPF records or DKIM signature failures.



Improving Email Deliverability


Interpreting DMARC check results effectively and making necessary adjustments can significantly improve email deliverability. Here are some steps to enhance deliverability:


Implementing SPF and DKIM Correctly


Ensure that SPF and DKIM records are correctly configured. For SPF, include all legitimate IP addresses that send emails on behalf of your domain. For DKIM, generate and publish DKIM keys properly and ensure they are included in outgoing emails.


Monitoring and Adjusting DMARC Policies


Regularly monitor DMARC reports to identify any issues with email authentication. Start with a DMARC policy of "none" to gather data without affecting email delivery. Gradually move to stricter policies like "quarantine" or "reject" as you gain confidence in your email authentication setup.


Keeping DNS Records Updated


Maintain up-to-date DNS records for SPF, DKIM, and DMARC. Any changes in your email infrastructure, such as new email service providers, should be reflected in these records to ensure continuous email deliverability.


Educating Users and Staff


Educate your employees and users about email authentication and the importance of using authorized email services. Awareness can prevent misconfigurations and reduce the chances of legitimate emails being marked as spam.


Common DMARC Issues and Troubleshooting Tips


Implementing DMARC can sometimes be challenging due to various issues that may arise. Understanding these common problems and how to troubleshoot them can help ensure a smooth implementation and ongoing management of your email authentication.


Misconfigured SPF Records


One of the most common issues is misconfigured SPF records. SPF records must include all IP addresses that are authorized to send emails on behalf of your domain. If any legitimate IP address is omitted, emails sent from that IP address will fail the SPF check. To troubleshoot this, review your SPF record to ensure it includes all necessary IP addresses. Use tools like MXToolbox to test your SPF record for correctness and completeness. Also, remember that SPF records should be concise and within the 10 DNS lookup limit to avoid excessive DNS queries.



DKIM Signature Failures


DKIM signature failures occur when the email's DKIM signature does not match the public key published in your DNS records. This mismatch can be due to several reasons, including changes to the email content after it is signed or misconfigurations in the DKIM setup. To resolve DKIM signature issues, verify that your DKIM keys are correctly generated and published. Ensure that your email server is signing outgoing emails with the correct DKIM key and that no changes are made to the email content after it is signed.


Inconsistent DMARC Reports

Inconsistent or unclear DMARC reports can hinder your ability to diagnose authentication issues. This inconsistency can arise from incorrect report formats or issues with the reporting mechanism itself. To address this, use a reliable DMARC reporting tool that can aggregate and interpret DMARC reports effectively. Ensure that your DMARC record includes the correct email address for receiving reports. Regularly review the reports to identify and resolve any anomalies. Reach out to this site for more details.