What Causes a DMARC Fail? Common Causes & Quick Fixes

If your emails are landing in spam folders, getting rejected, or failing to reach recipients altogether, a DMARC fail could be the culprit. DMARC (Domain-based Message Authentication, Reporting, and Conformance) relies on both SPF and DKIM authentication to verify that emails sent from your domain are legitimate.

When either of these protocols is misaligned or misconfigured, DMARC fails, and the consequences can range from reduced deliverability to complete email rejection.

However, most DMARC failures stem from fixable misconfigurations across your email services. In this guide, we’ll break down what a DMARC fail means, why it happens, the impact it can have on your business, and exactly how to fix it.

What Does DMARC Failure Mean?

DMARC failure occurs when an email fails to pass the name-sake authentication protocol. This happens when neither SPF (Sender Policy Framework) nor DKIM (DomainKeys Identified Mail) can verify that the email is legitimately sent from your domain.

When DMARC fails, depending on your policy settings, the email may be:

• Delivered normally (p=none policy)
• Quarantined to spam/junk folder (p=quarantine policy)
• Rejected completely (p=reject policy)

The impact on your organization includes reduced email deliverability, damaged sender reputation, potential loss of business communications, and increased vulnerability to domain spoofing attacks.

Common Causes of DMARC Failure

Most DMARC failures stem from misconfigurations across email services that aren’t fully aligned with your domain. Understanding the root cause is the first step toward fixing the problem. Here are the most common reasons behind a DMARC fail.

SPF and DKIM misalignment

Proper SPF and DKIM alignment is essential to secure your domain and prevent misuse.

DMARC requires that at least one of these protocols — SPF or DKIM — aligns with the domain in the “From” header. If neither aligns, the result is a DMARC failure.

This is one of the most frequent causes and often happens when organizations use third-party email services that send on their behalf but don’t properly align with the root domain.

Misconfigured third-party senders

Misconfigured third-party senders can lead to DMARC failures if these services are not explicitly authorized in your SPF record or DKIM settings.

Many businesses use platforms like marketing automation tools, CRMs, helpdesk software, and transactional email services to send emails on their behalf. If these services aren’t properly configured to align with your domain’s authentication, every email they send risks triggering a DMARC fail.

Expired or missing DKIM keys

Expired or missing DKIM keys can cause DMARC failures because signatures won’t validate without them.

DKIM keys have a lifespan, and if they’re not rotated or renewed before they expire, the digital signature attached to your outgoing emails becomes invalid. Without a valid DKIM signature, receiving servers can’t verify the integrity of your message, resulting in a DMARC failure.

Suggested read: How To Set Up DKIM: Clear Steps You Can Follow Today

Multiple SPF records

Multiple SPF records can lead to DMARC failures since DMARC requires a single, valid SPF record to function correctly.

If your domain’s DNS has more than one SPF record, receiving servers may not know which one to reference, causing SPF checks to fail outright. This is a surprisingly common issue, especially when different teams or vendors add their own SPF records without consolidating them.

Email forwarding issues

Email forwarding can trigger DMARC failures because the forwarding server may change the original sender’s IP address, leading to SPF check failures.

When an email is forwarded, the “envelope from” address or headers may also be modified, breaking SPF alignment. Since the forwarding server’s IP is not included in the original sender’s SPF record, the email fails authentication, even though it was originally sent from a legitimate source.

Subdomain misalignment

Misalignment between subdomains and the root domain can cause DMARC failures if policies are only applied to the root domain.

For example, if your DMARC policy covers “yourdomain.com” but emails are being sent from “mail.yourdomain.com” without a separate policy or proper alignment, those emails may fail DMARC checks.

Organizations with complex email setups across multiple subdomains need to ensure consistent authentication across all of them.

Domain spoofing

Domain spoofing can result in DMARC failures as unauthorized sources do not pass SPF and DKIM authentication checks. If someone is impersonating your domain to send phishing or spam emails, those messages will naturally fail DMARC, which is exactly what the protocol is designed to catch.

While this type of DMARC failure isn’t a problem on your end, it’s a critical signal that your domain is being targeted, and it underscores the importance of monitoring your DMARC reports.

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What Happens When DMARC Fails?

When DMARC fails, the outcome depends entirely on the DMARC policy you’ve set for your domain. Your policy tells receiving mail servers how to handle emails that don’t pass authentication, and each level carries different consequences.

p=none: Monitoring only

With a DMARC policy set to p=none, emails that fail DMARC are still delivered, but they frequently land in the spam folder rather than the inbox. This policy is designed for monitoring.

It allows you to collect DMARC reports and identify authentication issues without disrupting your email flow. While it’s a safe starting point, keeping p=none long-term leaves your domain vulnerable since it doesn’t actively block unauthorized senders.

p=quarantine: Sent to spam

Under a DMARC policy of p=quarantine, failed emails are sent to the recipient’s spam folder. This reduces visibility and user engagement because your legitimate emails may end up buried alongside junk mail.

While this policy offers more protection than p=none, it can still hurt your business if legitimate emails are failing due to misconfigurations rather than actual spoofing.

p=reject: Blocked entirely

A DMARC policy of p=reject will result in receiving servers completely blocking the email, preventing it from reaching the recipient at all. This is the strictest and most secure policy. It stops phishing and spoofing attempts dead in their tracks.

However, if your SPF and DKIM aren’t properly configured, a p=reject policy will also block your own legitimate emails, which can severely disrupt business communications.

Impact of DMARC Failures on Your Business

DMARC failures pose significant challenges for businesses that depend on email for communication. The consequences can affect your reputation, revenue, and security. Here’s how a DMARC fail can impact your organization.

Reduced email deliverability

DMARC failures can result in legitimate emails being blocked or rejected by inbox providers, impacting business communications. Whether your emails land in spam or get rejected entirely, the result is the same: your messages aren’t reaching the people who need to see them.

For businesses that rely on email for sales, marketing, customer support, or transactional communications, this directly translates to lost opportunities.

Damaged sender reputation

Repeated DMARC failures can harm your domain’s sender reputation, making it harder for even authenticated emails to reach the inbox.

Mailbox providers like Google and Microsoft track your domain’s authentication history. When they see a pattern of DMARC failures, they begin treating your domain as less trustworthy. That means even properly configured emails may start facing deliverability issues over time.

Lower open rates and customer engagement

DMARC failures can lead to emails being sent to spam folders, reducing open rates and customer engagement.

If your marketing campaigns, invoices, order confirmations, or important business updates are consistently landing in spam, your audience simply won’t see them. This can lead to missed revenue, frustrated customers, and a decline in overall engagement metrics.

Increased phishing and spoofing risk

A high DMARC fail rate increases the risk of phishing attacks and domain spoofing, eroding customer trust. If your domain is being spoofed, unauthorized sources will fail DMARC checks, but without a strict enforcement policy, those spoofed emails may still reach recipients.

This puts your customers, partners, and employees at risk of falling for fraudulent messages sent under your brand’s name.

Long-term deliverability damage

DMARC failures can signal to mailbox providers that a domain is not trustworthy, which can have long-term implications for email deliverability. Rebuilding a damaged sender reputation takes significant time and effort.

The longer DMARC failures go unresolved, the harder it becomes to regain the trust of inbox providers and ensure your emails consistently reach the inbox.

How to Fix a DMARC Fail

A DMARC fail can disrupt email delivery, damage sender reputation, and leave your domain vulnerable to spoofing. Fixing it requires understanding why the failure occurred and making the right adjustments to your email authentication setup.

Follow these key steps to restore proper DMARC alignment:

Step 1: Start with a relaxed DMARC policy (p=none)

With a none policy, you can begin by monitoring your domain with DMARC (RUA) Aggregate Reports and keep a close eye on your inbound and outbound emails, this will help you respond to any unwanted delivery issues. This will allow legitimate messages to reach your recipients even if DMARC fails for them.

However, this leaves you vulnerable to phishing and spoofing attacks.

Step 2: Ensure Proper SPF and DKIM Alignment

Check your DNS record for any errors, and combine your DMARC implementations with both DKIM and SPF for maximum security and reduced risk of false negatives. 

You can use a free DMARC checker tool to find errors in your DMARC syntax or DNS record formations. These may include extra spaces, spelling mistakes, etc. 

Use both SPF and DKIM Alignment 

Using both DKIM and SPF in conjunction provides a layered approach to email authentication. DKIM verifies the integrity of the message, ensuring it hasn’t been tampered with, while SPF verifies the sending server’s identity. Together, they help establish trust in the email’s source, reducing the risk of spoofing, phishing, and unauthorized email activity.

Step 3: Strengthen Your Defense with Enforcement

After that, we help you shift to an enforced policy that would ultimately aid you in gaining immunity against domain spoofing and phishing attacks.

Step 4: Protect with AI-Driven Threat Detection

Takedown malicious IP addresses and report them directly from the PowerDMARC platform to evade future impersonation attacks, with the help of our Threat Intelligence engine.

Step 5: Continuously Optimize with Forensic Reports

Enable DMARC (RUF) Forensic reports gaining detailed information about cases where your emails have failed DMARC so that you can get to the root of the problem and fix it faster.

Fix DMARC Fail With PowerDMARC

Dealing with DMARC failures can be complex, especially when you’re managing multiple sending services, third-party platforms, and evolving email infrastructure. PowerDMARC simplifies the entire process, from initial setup to ongoing monitoring and threat detection.

We help organizations correctly deploy DMARC by providing step-by-step guidance and automation tools that ensure your DMARC records, SPF, and DKIM authentication are properly configured and aligned from day one. This reduces the risk of misconfigurations that lead to DMARC failures and gets your domain on the path to full enforcement faster.

Once DMARC is in place, PowerDMARC continuously monitors your email traffic and generates real-time reports and alerts whenever a DMARC fail is detected.

Here’s what makes us unique:

• AI-driven threat intelligence and automated alerts that identify phishing and spoofing attempts in real time
• Step-by-step onboarding and implementation support to get DMARC, SPF, and DKIM right from day one
• Human-readable, actionable reporting that replaces complex XML data with clear insights
• Trusted by 5,000+ organizations worldwide to fix and prevent DMARC failures

Contact us to get started!

Frequently Asked Questions (FAQs)

1. What does DMARC stand for?

DMARC stands for Domain-Based Message Authentication, Reporting, and Conformance. It’s an email authentication protocol that helps protect domains from email spoofing, phishing, and other cyber attacks by verifying that emails are legitimately sent from authorized sources.

2. How to pass DMARC authentication?

To pass DMARC authentication, your emails must pass either SPF or DKIM and align with the domain shown in the “From” address. Ensure your sending IPs are authorized in SPF, DKIM is properly signed, and your DMARC record is correctly published in DNS.

3. How to fix no DMARC protection?

To fix no DMARC protection, publish a DMARC record in your domain’s DNS. Start with a monitoring policy (p=none) to collect reports, then gradually move to stronger enforcement (p=quarantine or p=reject) once you confirm all legitimate email sources are authenticated.

4. How to fix the DMARC fail error?

To fix a DMARC fail error, start by checking why the message failed authentication. Make sure SPF and DKIM are correctly set up and aligned with the sending domain. Then verify that your domain’s DMARC policy is published correctly in DNS and matches how your emails are sent. Once everything is aligned, monitor DMARC reports to confirm the issue is resolved.

• About
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Maitham Al Lawati

Cybersecurity Expert, CEO at PowerDMARC

Maitham is a tech entrepreneur, cybersecurity expert, CEO and Founder of PowerDMARC with 15+ years of industry experience. Maitham holds a Global MBA from the University of Manchester and various professional certifications including CISSP, CISM, CRISC, and ISC2 CCSP.

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