Step-by-step setup for maximum email security

Implementing DMARC doesn't have to be overwhelming. This comprehensive guide walks you through every step of deploying DMARC authentication in 2025, from initial setup to full enforcement with proven strategies that protect your domain without breaking email delivery.

Email-based threats like phishing and stolen email credentials account for 44% of data breaches according to Verizon [1], making robust email authentication critical for organizational security. Yet, DMARC implementation can seem over complex due to conflicting guidance concerning DNS records, authentication protocols, and correct DKIM and SPF setup.

DMARC implementation appears more complex than it actually is. With the right approach and proper guidance, organizations can deploy enterprise-grade email authentication that stops spoofing attacks while ensuring legitimate emails reach their destination.

Globally, 50.2% of public companies have reached full DMARC enforcement. [2]. Organizations without proper email authentication face increasing vulnerability as major email providers like Google and Yahoo now require DMARC for bulk senders, making implementation essential for email deliverability. Many organizations still avoid enforcing strong policies, with nearly 75% of senders using only monitoring mode (p=none) rather than active enforcement [5].

This guide will take you through the complete DMARC implementation process, step by step, with real-world insights and proven strategies that work. By the end, you'll have a robust email authentication system that protects your brand reputation and keeps your communications secure.

1. Audit and prepare: Inventory email sources and ensure SPF/DKIM are properly configured
2. Create your initial policy: Start with monitoring mode (p=none) to gather intelligence
3. Deploy and monitor: Publish your DMARC record and analyze incoming reports
4. Identify and authenticate: Add legitimate email sources and their authentication records to your DNS zone
5. Gradually enforce: Move from monitoring to quarantine, then reject policies
6. Maintain and optimize: Ongoing monitoring and policy refinement

Expected outcome: Complete protection against email spoofing with 99%+ legitimate email delivery rates

What you're doing: Publishing your first DMARC record in monitoring mode to begin collecting authentication data without affecting email delivery.

Example: v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com; ruf=mailto:dmarc-failures@yourdomain.com; pct=100

• Use addresses that can handle high incoming email volume
• Consider using a dedicated DMARC reporting service for easier analysis

• Access your DNS management console
• Create a new TXT record with hostname: _dmarc.yourdomain.com
• Enter your DMARC record as the value
• Set TTL to 3600 seconds (1 hour) for faster updates during testing

What success looks like: Your DMARC record is published and DNS propagation is complete (verify using dig or nslookup commands).

Troubleshooting: If DNS changes aren't propagating, check with your DNS provider about update timing. Some providers take up to 24 hours for changes to fully propagate globally.

What you're doing: Creating a comprehensive inventory of your email ecosystem and ensuring prerequisite authentication protocols are properly configured.

• Include your primary domain (e.g., company.com)
• List all subdomains used for email (e.g., marketing.company.com, support.company.com)
• Note any third-party services sending on your behalf

• Email marketing platforms (Mailchimp, Constant Contact, etc.)
• CRM systems (Salesforce, HubSpot, etc.)
• Transactional email services (SendGrid, Mailgun, etc.)
• Internal mail servers and applications
• Any automated systems that send notifications

• Make sure you do not have redundant SPF configurations by looking at DMARC reports
• Confirm DKIM signing is enabled for all sending services
• Test authentication using tools like Red Sift Investigate

What success looks like: You have a complete inventory of email sources and confirmed that SPF and DKIM are properly configured for all legitimate senders.

Troubleshooting: If you discover email sources without proper SPF/DKIM setup, configure these authentication protocols before proceeding with DMARC. Missing authentication will cause legitimate emails to fail DMARC checks.

What you're doing: Collecting and analyzing DMARC reports to understand your email authentication landscape and identify any issues.

• Allow time for email providers to generate and send reports
• Reports typically arrive daily from major providers
• Smaller providers may send reports less frequently

• Download XML reports from your designated mailbox
• Use DMARC analysis tools to convert XML to readable format or if you signed up for a reporting service, look at their console
• Look for patterns in passing vs. failing authentication

• Review sources failing SPF alignment
• Check for DKIM signature issues
• Note any unexpected IP addresses or sending sources

Focus on high-volume senders first. A single misconfigured marketing platform can generate thousands of DMARC failures, while a rarely-used notification system might only affect a few messages.

What success looks like: You're receiving regular DMARC reports and can identify which email sources are passing or failing authentication checks.

Troubleshooting: If you're not receiving reports, verify your rua/ruf email addresses are correct and that your mail server isn't blocking the incoming reports as spam.

What you're doing: Updating SPF and DKIM records to ensure all legitimate email sources pass DMARC authentication.

• Add missing IP addresses to your SPF record, but only if the return-path aligns
• Update include statements for third-party services
• Ensure SPF record doesn't exceed the 10 DNS lookup limit*

*Better still opt for a DMARC provider who overcomes the 10 DNS lookup like Red Sift OnDMARCRed Sift OnDMARC

• Enable DKIM signing for services that weren't configured
• Update DKIM selectors and public keys as needed
• Verify DKIM signatures are properly aligned with your domain

• Configure SRS (Sender Rewriting Scheme) or ARC (Authenticated Received Chain) if you forward emails
• Consider alternative authentication methods for complex routing
• Document any legitimate sources that cannot be authenticated

When updating SPF records, use the "include" mechanism for third-party services rather than listing individual IP addresses. This ensures automatic updates when providers change their infrastructure.

What success looks like: Your DMARC reports show 95%+ authentication pass rates for legitimate email sources, with only suspicious or clearly fraudulent messages failing.

Troubleshooting: If legitimate emails continue failing after SPF/DKIM updates, check for email forwarding, mailing list modifications, or third-party services that alter message content. Keep inmind you may not be able to do anything regarding most of these alterations.

Red Sift OnDMARC transforms complex, time-consuming manual DMARC implementation into a streamlined, guided experience. As the #1 DMARC solution in EMEA with a 4.9-star G2 rating, Red Sift has helped over 1,200+ organizations achieve full DMARC protection in 6-8 weeks.

• Automated report analysis: Instead of manually parsing XML files, OnDMARC provides clear, actionable insights with visual dashboards that make sense of complex authentication data
• Guided policy progression: The platform automatically recommends when to move from monitoring to quarantine to reject policies based on your authentication success rates
• Intelligent source discovery: OnDMARC identifies all email sources sending from your domain, including shadow IT services you might not know about
• One-click authentication: Simplified SPF and DKIM configuration with automatic updates when third-party services change their infrastructure
• Expert support: Access to Red Sift’s award-winning Customer Success who can guide you through complex scenarios and ensure smooth deployment

• Essential security: DMARC is no longer an optional choice for email authentication, but an essential prevention method against harmful phishing and spoofing techniques
• Complex email environments: Organizations with multiple domains, subdomains, and diverse email services
• Rapid deployment needs: When you need to achieve DMARC compliance quickly for regulatory or business requirements
• Limited internal resources: Teams that want enterprise-grade protection without dedicating significant internal technical resources
• Ongoing management: Organizations seeking continuous monitoring and optimization rather than one-time setup

What you're doing: Moving from monitoring mode to active enforcement, starting with quarantine and progressing to reject policies.

1. Transition to quarantine policy

Example: v=DMARC1; p=quarantine; pct=25;rua=mailto:dmarc-reports@yourdomain.com;ruf=mailto:dmarc-failures@yourdomain.com

• Start with 25% of failing messages affected
• Monitor for any legitimate emails being quarantined
• Gradually increase pct value: 25% → 50% → 75% → 100%

1. Monitor quarantine impact

• Check with users about missing emails
• Review spam folders for legitimate messages
• Analyze reports for any new authentication failures

1. Progress to reject policy

Example: v=DMARC1; p=reject; pct=25;rua=mailto:dmarc-reports@yourdomain.com;ruf=mailto:dmarc-failures@yourdomain.com

• Start with 25% and gradually increase
• This represents your final, most secure policy setting
• Fraudulent emails are completely blocked

Take your time with policy progression. Spending an extra week in quarantine mode is preferable to accidentally blocking legitimate business communications.

What success looks like: You've achieved p=reject with pct=100, and your DMARC reports show consistent authentication success for legitimate sources while blocking spoofing attempts.

Troubleshooting: If legitimate emails are being rejected, immediately reduce the pct value and investigate the authentication failure. Avoid rushing the progression as email deliverability is critical for business operations.

What you're doing: Creating processes for continuous DMARC monitoring and policy optimization to maintain long-term email security.

• Weekly analysis of DMARC aggregate reports
• Monthly review of authentication trends and new sources
• Quarterly assessment of policy effectiveness

• Monitor for sudden increases in DMARC failures
• Set up notifications for new, unknown email sources
• Track changes in authentication pass rates

• Update SPF records when adding new email services
• Rotate DKIM keys according to security best practices
• Review and update DMARC policies as your email infrastructure evolves

Document your DMARC configuration and processes. When team members change or new services are added, proper documentation ensures your email authentication remains intact.

What success looks like: You have established processes that maintain 99%+ authentication success rates while quickly identifying and addressing any new threats or configuration issues.

Troubleshooting: If you notice degrading authentication rates, first check for recent changes to email services or DNS records. Most DMARC issues stem from infrastructure changes that weren't properly coordinated.

• Why it happens: Pressure to quickly achieve compliance or security goals
• How to avoid: Always spend at least 2-3 weeks in monitoring mode analyzing reports
• If it happens: Immediately revert to p=none and restart the monitoring process

• Why it happens: Shadow IT services and forgotten automated systems
• How to avoid: Conduct thorough audits including all departments and legacy systems
• If it happens: Add newly discovered sources to SPF/DKIM records and monitor for additional unknowns

• Why it happens: Assumption that main domain DMARC covers all subdomains
• How to avoid: Explicitly configure authentication for each subdomain used for email
• If it happens: Create separate DMARC records for subdomains or ensure they inherit proper authentication

For organizations just starting: Begin with a single, low-volume subdomain to learn the process before applying to your main email domain. This reduces risk while building expertise.

For advanced implementations: Consider implementing BIMI (Brand Indicators for Message Identification) once you achieve p=reject. This displays your logo in supported email clients, further enhancing brand trust and recognition.

• Forensic report analysis: Use ruf reports to get detailed information about specific authentication failures, helping identify sophisticated spoofing attempts
• Subdomain policy inheritance: Strategically use sp= tags to set different policies for subdomains while maintaining centralized management
• Percentage-Based Rollouts: Use pct= values for testing policy changes, allowing you to measure impact before full deployment

• Authentication pass rate: 95%+ of legitimate emails passing DMARC checks
• Policy compliance: Successfully operating at p=reject with pct=100
• Threat blocking: Documented reduction in spoofing attempts and phishing emails
• Email deliverability: Maintained or improved inbox placement rates
• Report coverage: Receiving consistent DMARC reports from major email providers

• Week 1-2: Initial monitoring and report collection, identifying authentication gaps
• Week 3-4: Authentication fixes implemented, moving to quarantine policy
• Week 5-6: Gradual enforcement progression, achieving p=reject policy
• Ongoing: Continuous monitoring with 99%+ authentication success rates

Business Impact Metrics Research shows that DMARC implementation has led to significant improvements in email security, with Google reporting a 75% drop in unauthenticated messages after enforcing bulk sender authentication requirements in 2024 [3].

Additionally, email authentication protocols like SPF, DKIM, and DMARC are essential for achieving inbox placement with major mailbox providers, with DMARC adoption increasing by 11% in 2024 as organizations recognize the importance of proper authentication [4].

• Document your DMARC configuration and processes for future team members
• Set up regular monitoring schedules and assign responsibility for report analysis
• Consider implementing additional email security measures like BIMI for enhanced brand protection

• Implement SPF, DKIM, and DMARC for all domains and subdomains
• Consider advanced threat protection solutions for inbound email security
• Explore email encryption options for sensitive communications

• Quarterly reviews of authentication performance and policy effectiveness
• Regular updates to SPF records when adding new email services
• Annual security assessments including email authentication protocols

The email threat landscape continues evolving, with new attack vectors emerging regularly. However, with proper DMARC implementation and ongoing monitoring, you've established a robust foundation that protects your organization's email communications and brand reputation.

DMARC implementation requires ongoing attention as a continuous security practice rather than a one-time project. The investment in proper email authentication pays dividends in preventing security incidents, maintaining brand trust, and reliable email communications that support your business objectives.

[1] Verizon. "2025 Data Breach Investigations Report." https://www.verizon.com/business/resources/reports/dbir/ 

[2] Red Sift. "Red Sift's guide to global DMARC adoption" https://redsift.com/guides/red-sifts-guide-to-global-dmarc-adoption 

[3] Google. "New Gmail protections for a safer, less spammy inbox" https://powerdmarc.com/email-phishing-dmarc-statistics/

[4] Mailgun. "Email Authentication Requirements in 2025." https://www.mailgun.com/state-of-email-deliverability/chapter/email-authentication-requirements/

[5] Red Sift. BIMI Radar. https://bimiradar.com/glob