Why did my email campaign perform poorly after setting up DMARC?
Michael Ko
Co-founder & CEO, Suped
Published 8 Jul 2025
Updated 19 Aug 2025
6 min read
Setting up DMARC (Domain-based Message Authentication, Reporting, and Conformance) is a crucial step toward enhancing email security and deliverability. It's designed to protect your domain from impersonation, phishing, and spoofing. However, sometimes, after implementing DMARC, email campaign performance unexpectedly declines, leading to high bounce rates and low open rates. This can be confusing, as DMARC is meant to improve, not hinder, deliverability.
The good news is that DMARC itself isn't usually the direct cause of poor performance. Instead, it often reveals pre-existing authentication or deliverability issues that were previously hidden or went unnoticed. The sudden drop you observe is typically a symptom of underlying misconfigurations with SPF (Sender Policy Framework) or DKIM (DomainKeys Identified Mail) that DMARC now brings to light.
When you implement DMARC, particularly with a policy like p=none, you're telling receiving mail servers to simply monitor what happens with emails sent from your domain. This policy doesn't instruct them to block or quarantine messages that fail DMARC authentication. Instead, it's designed to provide you with DMARC reports, which contain valuable data about your email streams and any authentication failures.
However, even a p=none policy can still influence deliverability. Some mailbox providers, like Google and Microsoft, may interpret the presence of a DMARC record, even a monitoring one, as an indication that the sender is serious about authentication. If your SPF or DKIM records are misconfigured and emails are failing authentication, these providers might be more likely to filter (or blocklist) your emails, even with a p=none policy.
The underlying issue is often a failure in DMARC alignment. For DMARC to pass, an email must pass either SPF or DKIM authentication, and the domain in the From header (RFC5322.From) must align with the authenticated domain (either the SPF domain or the DKIM signing domain). If these don't match or the underlying SPF or DKIM checks fail, DMARC will fail. This can result in emails going to the spam folder or being rejected outright, depending on the receiving server's strictness and your DMARC policy.
The purpose of DMARC
DMARC is designed to help you gain visibility into your email ecosystem. It reports on which sources are sending email using your domain and whether those emails are passing or failing authentication checks (SPF and DKIM). While it doesn't directly fix deliverability issues, it provides the data necessary to identify and troubleshoot them.
Common technical misconfigurations and authentication failures
The primary culprits behind a sudden drop in email performance after DMARC implementation are often technical misconfigurations of SPF and DKIM. Even a minor error in your DNS records can lead to authentication failures. For example, if your SPF record is missing an authorized sending IP or if your DKIM record's public key doesn't match the private key used by your email service provider, emails will fail authentication.
SPF errors: Exceeding the 10-DNS-lookup limit, including incorrect IP addresses or domains, or having multiple SPF records for a single domain will cause SPF to fail.
DKIM errors: An incorrectly published DKIM public key, an expired key, or a DKIM body hash mismatch can cause DKIM authentication to fail. Additionally, using the wrong DKIM selector in your DNS can lead to issues.
DMARC record issues: While less common with a p=none policy, syntax errors in the DMARC record itself can prevent it from being correctly interpreted.
It's crucial to confirm that SPF and DKIM are properly configured and aligned before enabling DMARC. A common misconception is that DMARC fixes these issues, but it actually relies on them being correct. If your campaign performance dropped, it's highly likely that your emails were already failing SPF or DKIM, and the DMARC record (even if p=none) made this visible to more mail servers, leading to increased filtering into spam or outright rejections.
This is why monitoring your DMARC reports is paramount. These reports, sent to the email address specified in your rua tag, contain aggregated data that shows which emails are failing DMARC and why. Analyzing these reports will provide the specific details needed to diagnose SPF and DKIM issues, or identify any unauthorized senders spoofing your domain. Without parsing these reports, it’s like flying blind.
Considering broader deliverability factors
While DMARC, SPF, and DKIM are critical for technical email authentication, email deliverability is a multi-faceted challenge. Your sender reputation, content quality, and email list hygiene also play significant roles. Even with perfect DMARC setup, a poor sender reputation can lead to emails landing in the spam folder or on a blocklist (or blacklist).
High bounce rates often indicate underlying list quality issues, such as outdated or invalid email addresses. Sending to these addresses can negatively impact your sender reputation, triggering spam filters. Similarly, low engagement (low open and click rates) or high complaint rates signal to mailbox providers that your content isn't relevant or desired by recipients. These behavioral factors can independently hurt your deliverability, regardless of your DMARC status. Learn more about why marketing emails go to spam.
Before DMARC
Email authentication (SPF/DKIM) might be misconfigured, but the impact is less visible. Some emails might be quietly sent to spam or rejected without clear reasons.
Sender reputation issues may exist but are harder to diagnose without granular feedback.
After DMARC (p=none)
Authentication failures are now reported, providing data on why emails are failing SPF or DKIM alignment. This visibility helps pinpoint the exact problem.
Mailbox providers may treat unauthenticated mail more strictly, potentially increasing bounces or spam placement for previously accepted, but unauthenticated, emails. You can troubleshoot failed email delivery using this data.
To effectively troubleshoot, always check your bounce messages for specific error codes or explanations. These messages often provide direct clues as to why an email was rejected, such as authentication failures, content issues, or recipient-side blocklisting. You can also monitor your sender reputation using tools like Google Postmaster Tools, which provide insights into your domain's spam rate, IP reputation, and DMARC failures.
Key takeaways for DMARC implementation
A sudden dip in email campaign performance after implementing DMARC is almost always a sign that DMARC is doing its job by highlighting existing authentication vulnerabilities. It's not the DMARC record itself causing the problem, but rather the underlying SPF and DKIM failures that are now being enforced or reported more strictly by receiving mail servers.
To fix this, focus on a comprehensive review of your SPF and DKIM setups, address any alignment issues, clean your email lists, and consistently monitor your DMARC reports. This proactive approach ensures that DMARC successfully protects your brand and improves your overall email deliverability, rather than appearing to hinder it.
Views from the trenches
Best practices
Always configure SPF and DKIM correctly and ensure alignment before publishing any DMARC record.
Start DMARC deployment with a `p=none` policy to gather data and identify legitimate email flows.
Use a dedicated email address for DMARC reports that is not an active operational inbox.
Analyze DMARC reports regularly to understand authentication trends and identify failing sources.
Common pitfalls
Publishing a DMARC policy of `p=quarantine` or `p=reject` without first verifying SPF/DKIM alignment.
Google and 
Microsoft, may interpret the presence of a DMARC record, even a monitoring one, as an indication that the sender is serious about authentication. If your SPF or DKIM records are misconfigured and emails are failing authentication, these providers might be more likely to filter (or blocklist) your emails, even with a p=none policy.
