Technical Deliverability: How to Fix DMARC p=reject When Email Campaigns Stop Sending and Revenue Drops

When email campaigns suddenly stop sending with no errors, no spikes in bounces, and no activity in your inbox reports, it is a clear sign that something is wrong.

This usually is not a platform glitch. More often, it is your domain being flagged by inbox providers and in many cases, the issue comes down to one setting in your DNS. DMARC set to p=reject.

For brands that depend on email as a revenue channel, this type of blockage is significant. Email service providers are not trying to shut down campaigns. They are enforcing security measures that you may have accidentally put in place, designed to protect inboxes from abuse.

So if your domain has encountered a DMARC p=reject issue, this guide explains why it occurs, what commonly causes it, and how to resolve it without harming your sender reputation.

To overcome email deliverability issues, it is crucial to understand how email authentication and trust work behind the scenes.

The Role of Email Gatekeepers

Inbox providers like Google, Yahoo, Apple Mail, and Microsoft don’t just receive your emails. They vet them. These email Gatekeepers are programmed to protect their users from phishing, spam, and impersonation attempts, which means they check whether your email is properly authenticated.

So what does that vetting process look like?

1. They inspect your sender domain.
2. They check whether your message is coming from an approved source.
3. They evaluate your email sender reputation based on historical engagement, spam complaints, and technical configurations.

Gatekeepers make decisions in milliseconds. And if something doesn’t check out, your message gets flagged, filtered, or blocked entirely.

Why Email Authentication Is Key

To earn trust with inboxes, you need to play by the rules—specifically the rules set by email authentication standards like SPF, DKIM, and DMARC.

• SPF (Sender Policy Framework) tells inboxes which IP addresses are authorized to send on behalf of your domain.

• DKIM (DomainKeys Identified Mail) cryptographically signs your emails so recipients know they haven't been tampered with.

• DMARC (Domain-based Message Authentication, Reporting & Conformance) is the enforcer. It tells inbox providers what to do when SPF or DKIM checks fail.

This is the reason why email authentication is key. Without it, your domain is prone to impersonation. With it, you can protect your brand and the people who trusted you with their email addresses.

What DMARC “p=reject” Actually Means

DMARC has three policy levels:

• p=none: Monitor mode. Collects data but doesn’t enforce anything.
• p=quarantine: Sends suspicious emails to spam.
• p=reject: Block unauthenticated messages entirely.

DMARC p=reject is the strictest level of enforcement. That's why if an email fails SPF or DKIM and does not align with DMARC rules, it is rejected outright. The message never reaches the inbox or the spam folder. It simply does not get delivered.

Inbox providers use this policy to prevent phishing, spoofing, and spam. And they’ll apply it whether you meant to enforce it or not if they suspect your domain is under threat.

Domain Spoofing: The Root Cause

So why would inboxes move to a DMARC p=reject stance against your brand?

It usually comes down to Domain Spoofing.

That’s when a bad actor uses your domain to send fake emails. If your domain lacks proper authentication records, you’re an easy target.

Even if your domain is not being actively spoofed, inbox providers may still reject your emails when they detect risky signals. It is a protective move. They would rather block a message that looks unsafe than risk letting harmful content through.

Common Triggers That Cause DMARC p=reject

There are several technical missteps that can trigger this policy:

• Sending from unauthorized domains or subdomains, such as a new subdomain without the right DNS setup.
• Missing or misaligned SPF/DKIM records.
• Third-party platforms are sending emails on your behalf without proper authentication (like Klaviyo or Braze).
• Using From addresses that do not align with the authenticated sending domain.

These issues will alert inbox providers that you may not have full control over your domain. When this occurs, your trust decreases, your email sender reputation suffers, and your messages begin to be treated as potential threats.

DMARC Requirements for Shopify Stores

Here’s where things get specific. The DMARC requirements for Shopify stores are often overlooked, and that’s a problem.

Many Shopify brands:

• Utilize various third-party apps to send transactional emails.
• Combine marketing and transactional emails under one domain
• Lack visibility into what tools are authenticating properly

This is the recipe for misalignment. That's why if one application sends an email using your domain without proper authentication, inbox providers will perceive this as a domain-level issue.

They do not care which specific tool has caused it; they only recognize a security gap. As a result, your sender reputation will suffer.

How This Impacts Revenue (Not Just Deliverability)

A DMARC p=reject policy is more than just a technical issue. It blocks your brand's ability to generate revenue.

• Your campaigns don’t reach inboxes.
• Your automations stall.
• Your email flows, like abandoned cart or post-purchase, quietly stop working.

The outcome could be a significant revenue loss that often occurs without prior warning. Deliverability takes a hit, and so does your retention.

When customers don’t hear from you, they disengage. And that's why this is a problem that impacts your entire retention strategy, not just your tech stack.

How to Fix and Prevent DMARC p=reject Issues

Solving this starts with visibility. Here’s what to do:

1. Audit all your sending sources (Klaviyo, Shopify, apps, etc.)
2. Align SPF, DKIM, and DMARC across every domain and subdomain
3. Set up DMARC monitoring tools to receive reports on authentication failures
4. Clean up unused platforms that still have send permissions

This isn’t a one-and-done fix. It requires ongoing attention, especially as your stack evolves. Think of it as an advanced deliverability discipline, something your brand grows into as you scale.

Why This Is Best Handled by a Full-Service Email Partner

Most brands do not notice these problems until revenue drops or email performance falls off a cliff. By then, damage is already done. This is where a full-service email marketing partner actually matters.

A good email marketing team does more than set up automations. They keep an eye on deliverability day to day. When something breaks, they fix it.

When something feels off, they take immediate action instead of waiting for it to escalate into a real problem.

This is because they view email infrastructure as something that requires ongoing attention rather than a one-time setup.

They also understand how authentication affects inbox placement and how both influence long-term growth. That understanding is what sits at the core of advanced retention services.

How a Klaviyo Agency Solves This Differently

Many brands assume that Klaviyo automatically manages authentication.

But what they didn't know was that if you have not updated your DNS records or coordinated with your web host, your protection is often only partial.

A Klaviyo agency understands how to:

• Ensure that DNS records are properly configured
• Manage multiple sending domains effectively
• Maintain consistent authentication across various email flows
• Tie technical health to strategic outcomes

This is essentially important for brands utilizing Klaviyo with Shopify, where several third-party applications intersect.

Conclusion: DMARC Isn’t the Enemy—It’s the Signal

Your deliverability did not break overnight. It was pointing to a deeper issue. One that can be fixed, only if you know where to look.

DMARC p=reject is a warning light, not the end of the road. It usually means your brand has moved past a basic email setup and now needs more advanced support.

Authentication isn’t just for IT teams. It’s a strategic advantage. If you want to consistently reach inboxes, increase conversions, and retain more customers, then understanding why email authentication is key becomes non-negotiable.

Want to stop deliverability problems before they happen? It starts by treating email like the revenue channel it is.

Let us help you overcome email deliverability issues before they cost you more customers.