There’s nothing more frustrating than spending hours crafting the perfect email campaign, hitting send, and then watching your open rates crawl at 2%.
You check your analytics. Thirty percent of your subscribers saw the email. But only 2% opened it.
That means the rest? They never even saw it in their inbox. It went straight to spam.
If you’re using MailWizz and your deliverability has been declining, you’re not alone. Let me walk you through the most common reasons MailWizz emails end up in spam — and how proper Amazon SES domain verification can fix most of them.
The Dirty Truth About MailWizz Deliverability
MailWizz is a powerful email marketing platform, but it has a reputation problem.
Because MailWizz is self-hosted and widely used, many mailbox providers treat emails from MailWizz-powered platforms with extra scrutiny. Gmail, Outlook, and Yahoo don’t know if you’re a legitimate sender running a professional service — or someone running a spam operation.
The difference comes down to one thing: authentication.
Mailbox providers check several things before deciding whether to deliver your email:
- Is the sending domain verified with the delivery service?
- Are DKIM signatures present and valid?
- Does the SPF record authorize this sending server?
- Does the DMARC policy exist and align with the domain?
- What’s the reputation of the sending IP and domain?
If any of these checks fail, your email gets marked as suspicious. And suspicious emails go to spam.
Reason #1: Your Domain Isn’t Verified with Amazon SES
This is the most common issue I see. Someone sets up MailWizz, connects Amazon SES, and starts sending. Everything works for a few days or weeks. Then deliverability drops off a cliff.
What happened? Amazon SES can send emails from unverified domains in sandbox mode, but as you scale, deliverability suffers. Without domain verification, Amazon SES doesn’t fully own your sending identity. DKIM signing might not be active. MAIL FROM settings might be using the default domain.
The fix: Complete Amazon SES domain verification for every domain you send from. This means adding the correct DKIM, SPF, and DMARC records to your DNS.
The Verify Sending Domain With Amazon SES for Mailwizz extension makes this process straightforward — it shows you exactly which records to add and lets you verify directly inside MailWizz.
Reason #2: Missing or Broken DKIM Signatures
DKIM is the single most important authentication protocol for email deliverability. Without valid DKIM signatures, your emails look unsigned and untrustworthy.
Here’s what a broken DKIM setup looks like:
- Your emails pass SPF (the server is authorized)
- But DKIM check fails (no valid signature)
- Gmail or Outlook sees the mismatch
- Your email gets flagged
The fix: Make sure DKIM is enabled in Amazon SES and the DNS records are correctly published. Amazon SES generates three DKIM records per domain. All three must be added to your DNS exactly as provided.
Pro tip: The extension’s one-click copy feature prevents the copy-paste errors that commonly break DKIM.
Reason #3: No SPF Record or Misconfigured SPF
SPF tells receiving servers which IP addresses are allowed to send emails for your domain. Without an SPF record, your domain has no authorization list — which means every email looks suspicious.
The fix: Add an SPF TXT record that includes Amazon SES’s sending infrastructure:
v=spf1 include:amazonses.com ~all
If you have multiple sending services, make sure to include all of them, but keep within the 10-lookup limit.
Reason #4: No DMARC Policy
DMARC is your domain’s instruction manual for receiving servers. Without a DMARC record, mailbox providers don’t know what to do when authentication checks fail. By default, they often default to spam.
The fix: Create a DMARC record at _dmarc.yourdomain.com. Start with monitoring mode (p=none) to gather data, then escalate to quarantine or reject once you’re confident.
v=DMARC1; p=quarantine; rua=mailto:[email protected]; pct=100
Reason #5: Sending from Unverified Domains in a Multi-Customer Environment
If you’re running MailWizz as a platform for multiple customers, this is a big one. Some of your customers might be sending from domains that aren’t fully verified. Those customers damage not only their own reputation but also your platform’s sending IP reputation.
The fix: Enforce domain verification. The Verify Sending Domain extension includes sending protection features that let you block or warn against sending from unverified domains. This protects your entire platform and keeps your deliverability healthy.
A Real Example
Let me share a scenario I’ve seen play out multiple times.
A MailWizz SaaS owner has 50 customers. 40 of them have properly verified domains. 10 don’t. Those 10 customers send campaigns with broken authentication. Gmail starts seeing a pattern of unauthenticated emails from the same sending IPs.
What happens next? Gmail’s algorithms start treating all emails from those IPs more skeptically — including the emails from the 40 customers who did everything right.
That’s why enforcing domain verification isn’t just about protecting individual customers. It’s about protecting your entire sending infrastructure.
Quick Troubleshooting Checklist
If your MailWizz emails are going to spam right now, here’s what to check immediately:
- Check your domain verification status — Log into Amazon SES and verify all sending domains show "Verified"
- Test DKIM — Use MXToolbox or similar tools to check your DKIM records
- Verify SPF — Make sure your SPF record includes your sending service
- Check DMARC — Confirm you have a DMARC record and the policy is appropriate
- Monitor reports — If DMARC is set up, review your aggregate reports for authentication failures
- Check blacklists — Use tools like MXToolbox to see if your IP or domain is blacklisted
The Bottom Line
Most MailWizz deliverability problems trace back to incomplete or incorrect domain verification. It’s not a content problem. It’s not a frequency problem. It’s an authentication problem.
The good news? It’s fixable.
By properly verifying your sending domains with Amazon SES and setting up DKIM, SPF, and DMARC correctly, you can dramatically improve your inbox placement. And with the right extension, the entire process takes minutes instead of hours.
Don’t let authentication issues kill your email campaigns. Take the time to verify your domains, and watch your open rates climb back to where they should be.
👉 Get the Verify Sending Domain for MailWizz extension and fix your deliverability today.
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