Security: Implement DMARC to Protect Your Domain from Email Spoofing and Phishing

While it’s not mandatory, implementing SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) has become common practice to protect your email from spoofing and improve deliverability. However, these alone are not sufficient, as SPF and DKIM do not enforce alignment between the "From" address and the authenticated domain. An attacker can send an email that passes SPF and DKIM checks but uses a different "From" address domain, potentially misleading recipients.

To minimize or prevent this scenario, you should enhance your email security by implementing DMARC (Domain-based Message Authentication, Reporting, and Conformance). DMARC policies instruct email providers on how to handle emails that fail DMARC validation, helping to protect your domain from spoofing and phishing attacks. Additionally, DMARC enables you to monitor the actions taken by email providers.

Here are the primary DMARC policies:

  • None: Allow the email to be delivered normally, even if it fails DMARC validation.
  • Quarantine: Mark the email as suspicious and send it to the junk/spam folder.
  • Reject: Block the email from being delivered.

If you’re new to DMARC, you can start by using a free DMARC monitoring tool from Postmark: DMARC monitoring tool

Disclosure: This entry is based on a collection of my personal notes, and some of the information may be outdated or no longer relevant. If you notice any inaccuracies, please let me know in the comments. I appreciate your feedback and will correct the entry as needed. :)

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