Full Alignment of DKIM, SPF and DMARC

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Increasingly, bulk senders are finding that their emails are no longer accepted by email providers despite having SPF and DKIM policies in place. Even with a DMARC record, the emails are silently rejected, and the reason for this is misaligned SPF and DKIM records.

Misalignment occurs when different domains are used in the message return-path and from headers.  In the past, this was permissible provided the return-path domain was validated by SPF and the from domain was DKIM signed. However, DMARC with full alignment requires that the same domain is used in the SPF and DKIM authentications.

Full alignment of DKIM, SPF, and DMARC records is crucial for enhancing email security, preventing unauthorized use of your domain and email acceptance.

What are DKIM, SPF, and DMARC?

  1. DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to your outgoing emails based on the domain in the message from header. The recipient’s mail server can verify this signature against the public key published in your DNS records. If the signature matches, it confirms that the email originated from your domain.
  2. SPF (Sender Policy Framework): SPF specifies which mail servers are authorized to send emails on behalf of your return-path domain. When an email arrives, the recipient’s server checks if the sending server’s IP address is listed in your SPF record. If it matches, the email passes SPF authentication.
  3. DMARC (Domain-based Message Authentication, Reporting, and Conformance): DMARC builds upon DKIM and SPF. It allows you to set policies for handling emails that fail authentication. DMARC also provides reporting on email delivery and authentication results.

Why Alignment Matters?

  1. Preventing Spoofing and Phishing: Alignment ensures that the domains used in DKIM and SPF match the domain in the “From” header of the email. This consistency prevents malicious actors from impersonating your domain and sending fraudulent emails.
  2. Enhancing Deliverability: Email providers increasingly rely on alignment to determine whether an email is legitimate. Proper alignment improves your email deliverability rates, as it signals to providers that your emails are authentic.
  3. Compliance with Email Providers: Major email providers like Google and Yahoo now require alignment for bulk email senders. Without alignment, your marketing or transactional emails may end up in spam folders.

Achieving Alignment

  1. DKIM Alignment:
    • The domain in the “d=” field of the DKIM signature must align with the domain found in the “From” header address.
    • Ensure that your DKIM setup correctly signs outgoing emails with the appropriate domain.
  2. SPF Alignment:
    • The domain used in SPF verification must match the domain in the “From” header of the message.
    • Review your SPF record to include all authorized sending servers (e.g., your email service provider’s servers).
  3. DMARC Alignment:
    • DMARC requires both DKIM and SPF to align with the “From” header domain.
    • Set up DMARC policies (p=) to enforce alignment (either “strict” or “relaxed”) and specify where to send aggregate and forensic reports.

Conclusion

In summary, aligning DKIM, SPF, and DMARC records ensures that your emails are authenticated and trustworthy. Implementing these protocols correctly helps protect your domain reputation, enhances deliverability, and reduces the risk of phishing attacks. Stay vigilant and regularly monitor your email authentication setup to maintain alignment and security. For more information on setting up your SPF, DKIM and DMARC records, contact your smtp hosting provider for the correct settings to be added in your domain’s DNS.

Remember, alignment is not just a technical requirement; it’s a critical step toward building trust with your recipients and maintaining a positive sender reputation.