Why your emails are going to spam and how to fix it: The complete SPF and DKIM setup guide

Imagine discovering that some of your legitimate business emails have never reached their destination, costing your organization thousands in lost opportunities and damaged relationships. This scenario isn't hypothetical, it's the reality for organizations that haven't properly implemented email authentication protocols like SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail).

Consider the IT manager who receives urgent reports that customers are receiving fraudulent emails appearing to come from the company domain, or the marketing director whose carefully crafted campaigns achieve dismal open rates because major email providers are automatically filtering their messages as suspicious. These situations highlight a critical gap in modern email security that affects both deliverability and brand protection.

Today’s email landscape has evolved dramatically, with providers like Gmail, Yahoo and Microsoft now requiring DMARC enforcement for bulk senders (those sending more than 5,000 emails daily) as of February 2024 [1]. These requirements aren't just recommendations, they're mandatory for maintaining email deliverability and protecting your domain from abuse.

Beyond obvious delivery failures, several hidden exposures exist that organizations often overlook:

• Subdomain vulnerabilities: Unprotected subdomains can be exploited for spoofing attacks even when your main domain is secured
• Third-party service gaps: Email marketing platforms, CRM systems, and customer support tools may send emails that fail authentication
• DNS configuration drift: Changes in email infrastructure often leave outdated authentication records that cause legitimate emails to fail validation
• Forwarded email failures: DKIM signatures can break when emails are forwarded through certain systems, causing authentication failures
• Mobile email client inconsistencies: Different email clients handle authentication differently, leading to inconsistent delivery experiences
• Reputation cascade effects: Authentication failures compound over time, progressively damaging your domain's sender reputation

Email authentication protocols serve as digital verification systems that prove your emails are legitimate and haven't been tampered with during transit. Think of SPF as a guest list for your email domain—it specifies which mail servers are authorized to send emails on your behalf. DKIM functions like a wax seal on official correspondence, providing cryptographic proof that your message originated from your domain and hasn't been altered.

• IP Address Authorization: Prevents unauthorized servers from sending emails using your domain by maintaining a whitelist of approved IP addresses and mail servers
• Spoofing Prevention: Helps prevent unauthorized use of your domain in the technical sending address (envelope sender), reducing certain types of phishing attempts
• Delivery Improvement: Helps email providers identify legitimate messages from your domain, improving inbox placement rates when combined with DKIM and DMARC
• Reputation Protection: Prevents your domain from being associated with spam or malicious emails sent by unauthorized parties
• Compliance Support: Provides one of the key authentication mechanisms required by email providers and industry standards, but works best in combination with DKIM and DMARC
• Third-Party Integration: Allows legitimate email services (marketing platforms, CRM systems) to send authenticated emails on your behalf
• Cost-Effective Security: Provides significant security benefits with minimal implementation costs and maintenance requirements

• Message Integrity Verification: Uses cryptographic signatures to ensure emails haven't been modified during transmission
• Domain Authentication: Proves that emails genuinely originate from your domain using public-key cryptography
• Enhanced Deliverability: Improves email provider trust, leading to better inbox placement rates and reduced spam filtering
• Tamper Detection: Identifies any unauthorized changes to email content, headers, or attachments during transit
• Brand Protection: Prevents cybercriminals from sending modified versions of your legitimate emails
• Forwarding Resilience: Maintains authentication integrity even when emails are forwarded through multiple systems (when properly configured)
• Long-Term Security: Provides cryptographic proof that remains valid throughout the email's lifecycle

• "SPF alone provides complete email security": SPF only validates sending servers, not message content or sender identity alignment
• "DKIM prevents all email spoofing": DKIM validates message integrity but doesn't prevent spoofing of the visible "From" address without DMARC
• "Authentication guarantees inbox delivery": While authentication significantly improves deliverability, content quality and sender reputation also matter
• "Small businesses don't need email authentication": Cybercriminals often target smaller organizations assuming they have weaker defenses

Understanding what email authentication does not cover is as important as knowing what it does [2]. These protocols don't protect against social engineering attacks, malware attachments, or phishing attempts that use legitimate but compromised accounts.

Determining your organization's email authentication status requires a systematic evaluation of your current configuration and delivery performance. This assessment reveals gaps that may be causing deliverability issues or security vulnerabilities.

Begin by examining your existing DNS records to identify current authentication protocols:

• Use tools like Red Sift's free Investigate tool to check your domain's SPF, DKIM, and DMARC records
• Document all authorized sending sources, including email marketing platforms, CRM systems, and third-party services
• Identify any subdomains used for email communication that may lack proper authentication
• Review DNS record syntax for errors that could cause authentication failures

Assess your current email delivery rates and reputation metrics:

• Analyze bounce rates, spam complaints, and delivery failures across different email providers
• Review email marketing platform reports for authentication-related delivery issues
• Monitor domain reputation using tools like Sender Score or Google Postmaster Tools
• Test email delivery to major providers (Gmail, Outlook, Yahoo) from different sending sources

Industry benchmarks indicate that properly authenticated emails achieve 15% higher deliverability rates compared to unauthenticated messages. Organizations with comprehensive authentication typically see average open rates of 22-24% compared to significantly lower rates for unauthenticated senders.

Evaluate your domain's vulnerability to spoofing and impersonation attacks:

• Search for existing spoofing attempts using your domain through threat intelligence platforms
• Review any customer reports of suspicious emails claiming to originate from your organization
• Assess the potential business impact of successful domain impersonation attacks
• Consider regulatory compliance requirements for your industry regarding email security

Red Sift OnDMARC stands out in the email authentication landscape by offering a user-friendly, comprehensive application that simplifies the complex process of implementing and managing SPF, DKIM, and DMARC protocols. Unlike competitors that focus on individual components, Red Sift provides an integrated approach that addresses the complete email authentication ecosystem.

Red Sift's primary advantage lies in its accessibility and automation. While traditional email authentication solutions require extensive technical expertise and ongoing manual management, Red Sift OnDMARC automates complex processes and provides clear, actionable guidance. The application consistently holds a 4.9-star rating on G2 with over 80 reviews, and has been recognized as the #1 DMARC vendor in Europe [3].

This recognition matters because it reflects real-world user satisfaction and successful implementation outcomes. Organizations using Red Sift OnDMARC typically achieve DMARC enforcement in 6-8 weeks, significantly faster than the industry average of 32 weeks with other solutions [4].

A real-world example illustrates Red Sift's effectiveness: ZoomInfo, a major B2B data platform, implemented Red Sift OnDMARC to manage their complex email infrastructure across multiple acquisitions and business units. Kevin Hopkinson, Head of Deliverability at ZoomInfo, noted: "With OnDMARC, we are able to scale and grow effectively as we add more employees and complete more acquisitions without worrying about shadow IT" [5].

Another case study involves TalkTalk, a UK telecommunications company, where Mark Johnson, Head of Customer Security, reported: "OnDMARC actually helped us discover and reject spoofing attacks we weren't aware of" [6]. This demonstrates how Red Sift's application not only prevents future attacks but also reveals existing security gaps.

Customer feedback consistently highlights Red Sift's superior support model and user experience. Unlike competitors that charge extra for premium support or offer it only for enterprise plans, Red Sift includes dedicated Customer Success Engineering for enterprise clients as part of their standard offering. Vinay Tekchandani, Technical Program Manager at Holland & Barrett, emphasized: "Red Sift makes email security easy. I've done implementations for DMARC before and this was by far the easiest. They take away all the headaches and make it painless" [7].

The application’s AI-powered assistant and automated troubleshooting capabilities distinguish it from competitors like Valimail, EasyDMARC, and PowerDMARC, which often require more manual intervention and technical expertise to achieve similar results.

Many organizations assume that comprehensive email authentication carries a prohibitive cost. However, in reality, the investment in proper email authentication typically represents a fraction of the potential losses from poor deliverability or successful spoofing attacks.

The average ROI of email marketing remains extremely high at $42 for every $1 spent [5]. When authentication issues cause even a 10% reduction in email deliverability, organizations can experience significant revenue impact. For a company sending 100,000 marketing emails monthly with a 2% conversion rate and $50 average order value, a 10% deliverability loss equals $10,000 in monthly lost revenue.

Several factors influence email authentication pricing:

• Organization size and email volume: Higher volumes typically require more sophisticated monitoring and management capabilities
• Infrastructure complexity: Multiple domains, subdomains, and third-party services increase implementation complexity
• Support requirements: Organizations with limited internal expertise benefit from managed services and dedicated support
• Compliance needs: Regulated industries may require additional reporting and audit capabilities
• Integration requirements: Complex IT environments may need custom integrations and specialized configuration

The hidden costs of poor email authentication often exceed the investment in proper solutions. These include lost revenue from failed email delivery, damage to brand reputation from spoofing attacks, potential regulatory fines, and the internal resources required to manage authentication issues reactively rather than proactively.

Certain scenarios dramatically increase the importance of robust email authentication beyond basic SPF and DKIM implementation. Organizations facing these situations should prioritize comprehensive solutions like Red Sift OnDMARC that provide advanced monitoring, automated management, and proactive threat detection.

• Merger and acquisition activity: Companies undergoing M&A face complex email infrastructure integration challenges, with multiple domains and legacy systems requiring unified authentication policies. Without proper management, authentication gaps can emerge during transitions, creating vulnerabilities that cybercriminals exploit.
• Regulatory compliance requirements: Organizations in healthcare, finance, and government sectors face strict email security mandates. A healthcare system failing to properly authenticate emails could face HIPAA violations if patient communications are compromised, potentially resulting in millions in fines.
• High-value target profile: Companies handling sensitive data, intellectual property, or financial transactions become prime targets for business email compromise attacks. A manufacturing company with valuable trade secrets experienced a $2.3 million loss when attackers used domain spoofing to redirect wire transfers.
• Global operations complexity: Multinational organizations with diverse email infrastructure, multiple languages, and varying regional requirements need sophisticated authentication management to maintain consistent security across all markets.

• Multiple third-party email services: Each additional email service provider increases authentication complexity and potential failure points
• Frequent infrastructure changes: Organizations with dynamic IT environments face ongoing authentication maintenance challenges
• Limited internal security expertise: Companies without dedicated email security specialists benefit significantly from managed authentication solutions
• High email volumes: Organizations sending large volumes of emails face greater reputational risk from authentication failures
• Customer-facing communications: Companies whose primary customer touchpoint is email cannot afford deliverability issues or spoofing attacks
• Brand reputation sensitivity: Organizations where trust is paramount (financial services, healthcare) face amplified damage from email security incidents

The consequences of underestimating email authentication needs far exceed the investment in comprehensive solutions. Across all organizations that experienced successful spoofing attacks in 2023, loss accrued to over 18 million USD, according to recent FBI data [7]. Beyond financial impact, the psychological peace of mind that comes from knowing your email communications are secure and deliverable provides immeasurable value to leadership teams and IT professionals.

Email authentication represents a foundational security investment that enables other business initiatives. Companies with robust authentication can confidently expand their email marketing efforts, implement new customer communication channels, and integrate additional business applications without worrying about security gaps or deliverability issues.

Effective email authentication requires regular assessment and adjustment. Organizations should conduct quarterly reviews using this checklist:

• Are all current email sending sources properly authenticated and monitored?
• Have any new third-party services been added that require authentication updates?
• Are DMARC reports being reviewed regularly for signs of spoofing attempts or configuration issues?
• Has the organization's email volume or infrastructure changed in ways that affect authentication requirements?
• Are authentication policies aligned with current industry best practices and regulatory requirements?

This systematic approach ensures that email authentication remains effective as organizations evolve and threats change.

Proper email authentication through SPF and DKIM implementation, enhanced by comprehensive DMARC policies, represents a critical investment in your organization's communication security and effectiveness. The evidence clearly demonstrates that organizations with robust email authentication achieve better deliverability, stronger security, and greater customer trust.

The choice between reactive email security management and proactive authentication implementation determines whether your organization controls its email destiny or remains vulnerable to evolving threats. In an environment where email remains the primary business communication channel and cyber threats continue to evolve, comprehensive email authentication isn't optional—it's essential for sustainable business operations.

Red Sift OnDMARC provides the comprehensive solution your organization needs to achieve rapid DMARC enforcement while maintaining excellent email deliverability. Our promise:

• Fastest time to enforcement: Achieve DMARC protection in 6-8 weeks with expert guidance and automated tools
• Comprehensive visibility: Monitor all email sources and identify unauthorized activity with detailed reporting and AI-powered insights
• Simplified management: Handle complex authentication requirements through an intuitive user interface that doesn't require deep technical expertise
• Ongoing protection: Benefit from continuous monitoring, automatic updates, and proactive threat detection

Explore our free email authentication tools to assess your current status, or learn more about implementing comprehensive DMARC protection for your organization.

[1] Red Sift. (2025) 2025 guide to mastering Microsoft, Google, and Yahoo’s bulk email sender requirements.

https://redsift.com/guides/bulk-email-sender-requirements 

[2] Red Sift. (2025) Red Sift’s definitive guide to email security.

https://redsift.com/guides/email-security-guide 

[3] Red Sift. (2025). Red Sift OnDMARC G2 Recognition. 

https://blog.redsift.com/news/europes-1-for-dmarc-red-sift-ondmarc-does-it-again/

[4] Red Sift. (2025). Red Sift OnDMARC.

https://redsift.com/pulse-platform/ondmarc 

[5] Red Sift. (2025) ZoomInfo achieves almost perfect email deliverability with OnDMARC.

https://redsift.com/resource-center/case-study/zoominfo 

[6] Red Sift. (2025) TalkTalk enjoys 4-6% better email engagement by implementing BIMI.

https://redsift.com/resource-center/case-study/talktalk 

[7] Red Sift. (2025) Holland & Barrett locks down its domains with Red Sift.

https://redsift.com/resource-center/case-study/holland-and-barrett 

[6] Red Sift. (2025). OnDMARC vs Valimail Comparison.

https://redsift.com/compare/redsift-vs-valimail

[7] FBI. (2024). Internet Crime Complaint Center Annual Report. https://www.ic3.gov/Media/PDF/AnnualReport/2023_IC3Report.pdf