DMARC vs. SPF and DKIM: Understanding the Complete Email Security Picture

In today’s digital world, email remains one of the most widely used communication channels, but it’s also a prime target for cyberattacks like phishing and spoofing. Businesses need to secure their email domains to protect against these threats. While terms like SPF, DKIM, and DMARC are often mentioned together, they serve different roles in email security. 

In this blog, we’ll break down how these three protocols—SPF, DKIM, and DMARC—work together to create a complete email security solution and why understanding each is essential for businesses. 

What Is SPF (Sender Policy Framework)?

SPF is the first layer of email authentication. It ensures that emails sent from your domain are only allowed if they come from approved IP addresses. By publishing an SPF record in your Domain Name System (DNS), you list all authorized mail servers allowed to send emails on behalf of your domain. 

How SPF Works: 

1. You create an SPF record that specifies which IP addresses or mail servers can send emails from your domain. 
2. When an email is received, the recipient’s mail server checks the sending IP address against the domain’s SPF record. 
3. If the IP address matches, the email passes the SPF check; if not, it may be flagged or rejected. 

Limitations of SPF: 

• SPF only works with the envelope sender (the hidden technical address used in the email transaction), not the visible sender address. So, attackers can still fake the visible sender. 
• SPF doesn’t protect against emails that are forwarded because forwarding can break the SPF check. 

What Is DKIM (DomainKeys Identified Mail)?

DKIM adds an additional layer of email authentication by attaching a cryptographic signature to each email. This signature allows the receiving server to verify that the email content hasn’t been altered in transit and that it truly comes from the domain it claims to be from. 

How DKIM Works: 

1. A DKIM signature is added to the email header by the sending server. 
2. The receiving server uses the public DKIM key published in the sender’s DNS to verify the signature. 
3. If the signature is valid, the email passes the DKIM check. 

Limitations of DKIM: 

• Like SPF, DKIM does not verify the visible “From” address. This means attackers could still use your domain in phishing attempts by spoofing the visible address while passing DKIM. 
• DKIM doesn’t provide a mechanism for reporting failed checks back to the domain owner, so you wouldn’t know if someone was spoofing your domain. 

What Is DMARC (Domain-based Message Authentication, Reporting & Conformance)? 

DMARC takes SPF and DKIM a step further by linking them and telling email receivers what to do if both fail. DMARC provides domain owners with the ability to: 

• Specify how their email should be authenticated using SPF and DKIM. 
• Define how to handle unauthenticated emails (whether to allow, quarantine, or reject them). 
• Receive reports on how their email domain is being used or abused. 

DMARC addresses the weaknesses of both SPF and DKIM by providing domain-level protection and visibility. 

How DMARC Works: 

1. DMARC policy: The domain owner publishes a DMARC policy in the DNS, specifying what action to take if an email fails both SPF and DKIM (none, quarantine, or reject). 
2. Alignment check: DMARC ensures that both SPF and DKIM align with the domain in the visible “From” address, eliminating the risk of spoofing. 
3. Reporting: DMARC sends reports to the domain owner, showing which emails are failing and from which IP addresses. 

Key Strengths of DMARC: 

• It verifies that both SPF and DKIM align with the domain in the “From” field, ensuring no one can fake your domain in the visible sender line. 
• DMARC gives you control over how unauthenticated emails are handled, allowing you to quarantine or block them. 
• It provides detailed reports on any suspicious email activity, helping you identify potential attacks. 

DMARC vs. SPF and DKIM: How They Work Together

While SPF and DKIM are essential for authenticating emails, DMARC brings these two protocols together to offer a more complete security solution. Here’s how they complement each other: 

1. SPF alone ensures the sending IP is authorized, but doesn’t verify the visible sender address. 
2. DKIM alone ensures the integrity of the email content and the identity of the sender, but can still be vulnerable to spoofing. 
3. DMARC ensures that both SPF and DKIM checks are in place and aligned with the domain’s “From” address, closing loopholes that attackers might exploit. 

In short, SPF and DKIM provide foundational email security, but DMARC completes the picture by adding enforcement and reporting capabilities. 

The Importance of DMARC for South African Businesses

Cyberattacks like phishing and domain spoofing are on the rise globally, and South Africa is no exception. Businesses here are increasingly falling victim to email-based attacks that compromise sensitive data, customer trust, and financial security. DMARC is not just a “nice-to-have” solution; it’s an essential component of modern cybersecurity strategy. 

By implementing DMARC with Turrito and Sendmarc, South African businesses can: 

• Protect their reputation: Stop cybercriminals from impersonating their brand to defraud customers or employees. 
• Reduce phishing attempts: By aligning SPF and DKIM with DMARC, businesses can prevent phishing attacks that target their domain. 
• Gain visibility into email activity: Receive reports on email authentication performance and potential abuse, empowering businesses to take proactive action. 

At Turrito, we make this process simple with Sendmarc. We help South African businesses implement DMARC seamlessly, ensuring they are fully protected from email-based threats. 

DMARC Is Essential for Complete Email Security

While SPF and DKIM are important building blocks for email security, DMARC is what ties them together to create a robust, foolproof solution. Without DMARC, your business remains vulnerable to attacks that could compromise your domain, reputation, and financial stability. 

By working with Turrito and Sendmarc, achieving DMARC compliance becomes straightforward, even for businesses without deep technical expertise. Let us take care of the technical details so you can focus on what matters most—growing your business. 

Ready to protect your domain from email-based attacks? Contact Turrito today to learn how DMARC, SPF, and DKIM can secure your email communications.