Why did my email open rate drop after implementing DMARC and what should I do?
Michael Ko
Co-founder & CEO, Suped
Published 23 May 2025
Updated 17 Aug 2025
7 min read
When you implement DMARC, you typically hope for a boost in email deliverability and, consequently, open rates. However, it's not uncommon to see the opposite happen, especially soon after deployment. This can be quite puzzling, particularly when you've just taken a significant step to improve your email security.
With new authentication requirements from major mailbox providers like Google and Yahoo, many senders are moving to implement DMARC. While this is crucial for protecting your domain from spoofing and phishing, a sudden drop in open rates can indicate underlying issues that need immediate attention.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol that tells receiving mail servers how to handle emails that fail SPF or DKIM alignment for your domain. It helps prevent unauthorized use of your domain in email, improving trust and sender reputation.
When you set up DMARC with a policy of p=none (monitoring mode), it means you're telling receiving servers to simply report on emails that fail DMARC alignment, without taking any enforcement action. This policy is generally recommended for initial implementation to gather data before moving to quarantine or reject. A drop in open rates immediately after setting p=none suggests a misconfiguration rather than the policy itself causing suppression.
A common reason for DMARC failure, even with p=none, is incorrect DKIM signing. For DMARC to pass, either SPF or DKIM must align with your domain. If your emails are signed by your Email Service Provider (ESP) (e.g., Mailchimp) with their own domain's DKIM and not your sending domain's, DMARC will fail alignment. This means that while your emails might still be delivered, they lack the strong authentication signal that DMARC is designed to provide.
DMARC failing means your email is not compliant
Even with a p=none policy, if your emails are failing DMARC authentication, they may still be routed to spam folders, especially by strict receivers. This is because the email lacks proper domain authentication, indicating a potential spoofing attempt or misconfiguration. This scenario can directly lead to a noticeable decrease in open rates, as recipients simply aren't seeing your messages in their inboxes. Confirm your DMARC is passing by checking your DMARC reports or using tools that analyze email headers.
Decoding the open rate dip
One reason for an apparent drop in open rates, even when deliverability hasn't actually worsened, relates to how email clients, particularly Gmail, handle open tracking. Open rates are typically tracked by a tiny, invisible pixel image loaded when an email is opened. If there's a change in your email authentication, such as switching DKIM signatures, mail servers might stop pre-fetching these pixels for a period. This means a legitimate email opening might not be recorded, leading to an artificially low open rate.
This phenomenon is not necessarily a sign that your emails are going to the spam folder. Instead, it indicates a change in how mailbox providers interact with your email's tracking elements. Over time, as reputation is re-established with the new authentication, pre-fetching should resume, and your reported open rates should normalize, assuming actual deliverability remains strong.
It’s crucial to distinguish between a drop in reported open rates and an actual drop in deliverability. A decrease in reported opens due to pixel pre-fetching issues is less concerning than emails consistently landing in spam or being rejected. The true measure of success lies in your emails reaching the inbox, regardless of tracking nuances.
Reported open rates
Consistent tracking: Open pixels are consistently pre-fetched.
Higher numbers: Open rates appear higher due to reliable pixel loading.
Misleading perception: May mask underlying deliverability issues if not properly authenticated.
After authentication changes
Potential dip: Open rates might show a temporary decrease.
Pixel pre-fetching affected: Mailbox providers may temporarily stop pre-fetching pixels.
Does not mean spam: This specific dip does not inherently mean emails are going to spam.
Actual inbox placement
Variable deliverability: Could have inbox issues despite reported open rates.
Risk of spoofing: Lack of DMARC leaves domain vulnerable.
Lower trust: Less trusted by mailbox providers without full authentication.
After authentication changes (with proper DMARC)
Improved security: Protects against unauthorized use of your domain.
Enhanced trust: Builds stronger sender reputation over time.
Better long-term deliverability: More likely to reach the inbox consistently.
Identifying underlying deliverability problems
To truly understand why your open rates dropped, you need to dive into the data. DMARC reporting, especially aggregate (RUA) reports, provides invaluable insights into your email streams, showing which emails are passing or failing SPF, DKIM, and DMARC. These reports will highlight if your emails are indeed failing DMARC and from which sending sources.
If you're sending to Gmail users, Google Postmaster Tools is an essential resource. It offers dashboards for IP reputation, domain reputation, spam rate, feedback loop data, and crucially, DMARC authentication status. A low domain or IP reputation score here, or a high spam rate, can directly explain a drop in open rates, as it indicates emails are being filtered to spam.
Beyond DMARC, always verify your SPF and DKIM records are correctly configured and aligned. A small typo or missing entry can lead to authentication failures. You can use an email deliverability tester to check if your emails are landing in the inbox or spam folder. This will give you a real-time snapshot of your email's journey and help diagnose issues quickly.
Failure Type
Description
Potential Impact on Open Rates
SPF alignment failure
SPF record might be missing sender, or the 'From' domain does not align with the SPF-authenticated domain.
Emails may go to spam; significantly reduced open rates.
DKIM alignment failure
DKIM signature domain does not align with the 'From' domain.
Emails may go to spam, especially with a strict DMARC policy.
No DMARC record
Your domain lacks a DMARC DNS record.
Emails vulnerable to spoofing, potentially lower inbox placement over time.
DMARC policy 'p=none'
Emails that fail authentication are reported but not rejected or quarantined.
Open rates may still drop if there are underlying issues like low domain reputation.
Restoring and enhancing email performance
The immediate step is to ensure your DKIM authentication is correctly set up for your sending domain, especially with your Email Service Provider. For example, if you use Mailchimptheir specific instructions to authenticate your domain. This ensures that your emails are properly signed and align with your DMARC record, fulfilling the authentication requirements of major mailbox providers.
If you've recently made significant changes to your sending infrastructure, or if your domain reputation has taken a hit, consider a domain warmup process. This involves gradually increasing your email volume over time to build trust with mailbox providers. Sending a large volume of emails from a newly authenticated or low-reputation domain can trigger spam filters and further depress open rates.
Beyond technical configurations, maintaining a clean and engaged email list is paramount. Regularly remove inactive subscribers who haven't opened your emails in a long time. Low engagement signals to ISPs that your emails are not valuable, negatively impacting your sender reputation. Focus on content that resonates with your audience to boost engagement.
Email deliverability is an ongoing process. Continuously monitor your DMARC reports, Google Postmaster Tools data, and your ESP's deliverability metrics. Pay attention to feedback loops and complaint rates. Adapt your sending practices based on this data. If you were sending cold emails, ensure your list is fully opted-in to avoid reputation damage. A healthy sender reputation is key to consistently high open rates.
Views from the trenches
Best practices
Always verify SPF and DKIM are aligned with your DMARC policy.
Set up DMARC reporting to gain visibility into email authentication results.
Utilize Google Postmaster Tools for Gmail-specific deliverability insights.
Implement a proper domain warmup if changing authentication methods or sending providers.
Common pitfalls
Assuming DMARC implementation alone will automatically increase open rates.
Not updating DKIM signing when enabling DMARC, leading to authentication failures.
Misinterpreting a temporary drop in reported open rates (due to pixel pre-fetching) as actual spam placement.
Neglecting to monitor DMARC reports and Postmaster Tools for performance issues.
Expert tips
Verify alignment: Double-check that your DKIM signature is correctly configured and aligns with your sending domain, as this is critical for DMARC compliance.
Monitor DMARC reports: Actively use DMARC reports to identify authentication failures and sources of non-compliant email.
Understand pixel pre-fetching: Be aware that Google's (and other providers') pre-fetching of tracking pixels can be affected by authentication changes, leading to an apparent dip in open rates that doesn't mean emails are in spam.
Patience and data: Recognize that improving deliverability and recovering open rates after changes takes time and requires careful interpretation of data from tools like Google Postmaster Tools.
Expert view
Expert from Email Geeks says that DMARC should not affect inbox placement or open rate if it is passing. Changes to DKIM signatures, however, can affect inbox placement and open rates because filters tie reputation to that identifier.
2024-09-07 - Email Geeks
Expert view
Expert from Email Geeks says that a 30-40% open rate is normal for standard senders and advises checking if Google Postmaster Tools are set up and if all compliance checks pass there.
2024-09-07 - Email Geeks
Navigating DMARC and open rates
Implementing DMARC is a critical step for modern email security and deliverability. While it's designed to improve trust, an immediate drop in open rates can be a sign of misconfiguration or the natural effect of mailbox providers adjusting to new authentication signals.
The key is to proactively monitor your DMARC reports and other deliverability metrics to differentiate between a tracking anomaly and an actual inbox placement issue. By ensuring proper SPF and DKIM alignment, nurturing your sender reputation, and maintaining a healthy list, you'll set the stage for long-term email success and genuinely higher open rates.
Google and 
Yahoo, many senders are moving to implement DMARC. While this is crucial for protecting your domain from spoofing and phishing, a sudden drop in open rates can indicate underlying issues that need immediate attention.
Mailchimp) with their own domain's DKIM and not your sending domain's, DMARC will fail alignment. This means that while your emails might still be delivered, they lack the strong authentication signal that DMARC is designed to provide.
Gmail, handle open tracking. Open rates are typically tracked by a tiny, invisible pixel image loaded when an email is opened. If there's a change in your email authentication, such as switching DKIM signatures, mail servers might stop pre-fetching these pixels for a period. This means a legitimate email opening might not be recorded, leading to an artificially low open rate.
