Fix Email Deliverability and Spoofing with Better DNS Security

Ensuring email deliverability and security requires a layered approach built on DNS, SPF, DKIM, and DMARC. These technologies work together to authenticate senders, prevent spoofing, and protect business communications from phishing and spam.

Without proper configuration, organizations risk email rejection by major providers and exposure to impersonation attacks. The foundation of secure email starts with robust DNS management, followed by the implementation of authentication protocols that signal trust to receiving servers.

How to Ensure Reliable Email Delivery and Security with DNS, SPF, DKIM, and DMARC

In this episode of the Demystifying Microsoft podcast, Nathan Taylor (SVP, Global Microsoft Practice Leader at Sourcepass MCOE) breaks down the technical requirements for secure email delivery. The discussion covers DNS management, the importance of DNSSEC, and practical steps for implementing SPF, DKIM, and DMARC to ensure compliance and protect business communications.

Timestamped Key Moments

• 00:00 — Introduction and overview of email security series
• 02:00 — Why DNS and DNSSEC matter for email authentication
• 07:00 — Tools and tips for securing your domain and learning DNSSEC
• 11:50 — How SPF, DKIM, and DMARC work together to protect email
• 18:50 — Common pitfalls with SPF and DKIM, and how to fix them
• 22:00 — DMARC enforcement, reporting, and EasyDMARC setup
• 27:00 — What’s next: BIMI, MTA-STS, TLS-RPT, and DANE
• Outro — How to get help and connect with Sourcepass MCOE

What is DNS and Why is it Critical for Email Security?

DNS (Domain Name System) acts as the internet’s phone book, directing traffic and enabling communication between domains. For email, DNS hosts the records that authentication technologies rely on. Poor DNS management can lead to lost domains, security breaches, and undelivered messages. Using a trusted provider and enabling DNSSEC helps protect domain integrity and supports advanced authentication.

How do SPF, DKIM, and DMARC Work Together to Prevent Email Spoofing?

SPF (Sender Policy Framework) lists authorized servers for sending email from a domain. DKIM (DomainKeys Identified Mail) cryptographically signs outgoing messages, verifying sender identity and message integrity. DMARC (Domain-based Message Authentication, Reporting, and Conformance) enforces alignment between SPF and DKIM, instructing receiving servers how to handle failures and providing reporting for compliance. Together, these records prevent unauthorized use and improve deliverability.

What Are Common Pitfalls and Solutions for Email Authentication?

• Only one SPF record should exist per domain; adding multiple records causes failures.
• Third-party senders (e.g., marketing platforms) must be included in SPF and DKIM records.
• MX record-based mail filters can disrupt DKIM signatures; API-based filtering is preferred.
• EasyDMARC and similar tools provide reporting to identify misalignments and guide remediation.

Take Control of Email Authentication with Sourcepass MCOE

Email authentication isn’t optional, it's foundational. SPF, DKIM, and DMARC work together to protect your domain from spoofing and ensure your messages reach their intended recipients. When paired with DNSSEC and a trusted DNS provider, these protocols help organizations maintain credibility and reduce risk across their Microsoft 365 environment.

If you're unsure whether your current setup meets modern standards or you're seeing deliverability issues, the Sourcepass Center of Excellence for Microsoft can help. Our team offers hands-on support for configuring authentication records, enabling DNSSEC, and deploying Defender for Office 365 features that align with your business needs.

Subscribe to the Demystifying Microsoft podcast for ongoing insights, and reach out today to chat with one of our experts to answer any questions or to schedule a free Office 365 email security assessment.

Explore the rest of the series:

• Part 1: How Microsoft 365 Secures Email with AI and Authentication

• Part 3: Email Security Best Practices with Microsoft Defender and EasyDMARC

• Part 4: Securing Email Delivery in Microsoft 365 with MTA-STS and DNSSEC