Best Practices for Implementing DMARC on

Gmail and Google Workspace

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a crucial email authentication protocol that helps prevent email spoofing, phishing, and domain impersonation. By utilizing DMARC in Gmail and Google Workspace, organizations can enhance their email security by ensuring that only authorized senders can send emails on behalf of their domain. This guide will provide effective strategies for implementing DMARC, SPF, and DKIM in Google Workspace. To explore further, simply click on the link.


Why DMARC is Essential for Google Workspace


Google Workspace users often face email spoofing, a method used by cybercriminals to make their messages seem like they come from a trusted domain. Without DMARC in place, these attackers can exploit your domain to send fraudulent emails, threatening your organization’s reputation and security. Implementing DMARC is crucial to reduce these risks.

  • You safeguard your domain against unauthorized access and usage.

  • You enhance the likelihood of email delivery, ensuring that messages do not end up in spam folders.

  • You acquire valuable information regarding the senders utilizing your domain through DMARC reports.



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Step 1: Set Up SPF (Sender Policy Framework)


What is SPF?

The Sender Policy Framework (SPF) is an email validation technique that specifies the authorized mail servers permitted to dispatch emails on behalf of your domain.


How to Configure SPF in Google Workspace

  • Log into your domain registrar (e.g., GoDaddy, Namecheap, Cloudflare).

  • Navigate to your DNS settings and locate the TXT records section.

  • Add or update your SPF record 

  • Save your changes and allow 24-48 hours for propagation.


SPF Best Practices

  • Consolidate multiple SPF records into one to maintain compliance.

  • For third-party services like Mailchimp or SendGrid, incorporate their SPF records with "include" mechanisms.

  • Ensure that the total DNS lookups remain below 10 to avoid authentication issues.


Step 2: Enable DKIM (DomainKeys Identified Mail)


What is DKIM?

DKIM employs cryptographic signatures to ensure email integrity by confirming that messages remain unchanged during transmission. Both Gmail and Google Workspace utilize DKIM signing for this purpose.


How to Configure DKIM in Google Workspace

  • Access the Google Admin Console at https://admin.google.com.

  • Go to Apps > Google Workspace > Gmail > Authenticate Email, select your domain, and click on Generate new record.

  • Copy the DKIM TXT record and update your domain's DNS settings accordingly.

  • Finally, return to the Admin Console and select Start Authentication.


Step 3: Implement DMARC for Google Workspace


What is DMARC?

DMARC enhances SPF and DKIM by allowing domain owners to dictate the handling of email failures and facilitating reporting to track unauthorized domain usage.


How to Configure DMARC

  • Log into your domain registrar and navigate to DNS settings.

  • Create a TXT record for DMARC with the following value:

    • v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com; 
    ruf=mailto:dmarc-forensics@yourdomain.com; sp=none;

    • p=none starts in monitoring mode (adjust later to quarantine or reject).

    • rua collects aggregate reports to monitor email activity.

    • ruf collects forensic reports for detailed failed email logs.

    • sp=none applies to subdomains (adjust to quarantine or reject as needed).

  • Save your changes and allow 24-48 hours for propagation.



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Step 4: Monitor DMARC Reports


Google Workspace does not provide built-in DMARC reporting, so use third-party tools like:


Google Postmaster Tools

  • DMARCian

  • Valimail

  • Agari


DMARC Report Analysis

  • Identify unauthorized senders using your domain.

  • Verify that SPF and DKIM pass for all legitimate emails.

  • Detect third-party services that need SPF/DKIM alignment.


Advanced DMARC Best Practices for Google Workspace


  • Ensure SPF, DKIM, and DMARC Alignment: For DMARC compliance in Google Workspace, either SPF or DKIM must pass, but for optimal security, both should be aligned.

    • SPF Alignment: The domain in the From address must match the SPF-authorized sending domain.

    • DKIM Alignment: The DKIM-signing domain should match the From domain.

  • Enforce DMARC on Subdomains: To protect your subdomains from attackers, implement DMARC policies by including sp=reject in your DMARC record.

  • Protect Against Lookalike Domains: Cybercriminals frequently register domains that closely resemble legitimate ones (e.g., yourd0main.com) for phishing attacks. Implementing Brand Indicators for Message Identification and enforcing DMARC can help thwart impersonation efforts.

  • DMARC Management: Explore DMARC automation solutions like Valimail, Dmarcian, or EasyDMARC to streamline reporting and enforcement.