How to Check Your Spam Complaints

If your email deliverability has taken a hit or your open rates are plummeting, there’s a good chance your emails are landing in spam. And one of the biggest culprits? Spam complaints — even when you're not technically “spamming.”

Spam complaints can silently erode your domain reputation, leading to long-term deliverability damage that’s hard to recover from. Most senders only realize the problem when it's too late — after their sender score drops or campaigns get blocked altogether.

In this article, we’ll show you exactly how to check your spam complaint rate, what counts as a high-risk threshold, and how to proactively manage it.

Why do spam complaints matter so much?

A spam complaint occurs when a recipient manually marks your email as spam — regardless of whether they opted in or not.

Even though it might seem like a small signal, mailbox providers like Gmail and Yahoo treat spam complaints as a major red flag. Just a few complaints, even per a thousand emails, can impact your:

• Inbox placement

• Domain reputation

• Email deliverability

Most ESPs and ISPs consider a spam complaint rate above 0.3% as a threshold for concern. Spam complaints affect not just one campaign — they compound over time, making it harder to get your future emails delivered, even if the content is high-quality.

How to check spam complaints in Mailmodo

While Mailmodo doesn't label a metric specifically as "Spam Complaints" in the UI, it provides you with everything you need to track and investigate your spam rate using a combination of campaign analytics and Google Postmaster. Here’s how you can check your spam complaints.

Integrate Google Postmaster (via Mailmodo)

For detailed spam complaint insights, you can connect your sending domain with Google Postmaster via Mailmodo. This gives you direct access to the complaint data mailbox providers use to evaluate your domain.

If you’ve not set it up, you’ll need to do that first. You can check out our complete guide on How to set up Google Postmaster for your domain.

If yo’ve already done that, you can head over to the Google Postmaster Tools Spam dashboard to check the spam complaints that you’ve received on your domain.

The spam dashboard will show you a graph that shows 3 lines:

• The blue lines that shows the number of spam complaints received

• The yellow line that shows 01% percent mark

• The red line that shows the 0.3% that needs to be avoided at all cosrs

Comparing the date of the rise of the graph, you can easily identify which campaigns are causing spam complaints.

What’s a “safe” spam rate?

Gmail and other providers don’t share exact thresholds publicly, but based on industry norms and Mailmodo’s internal quality controls:

Conclusion

Spam complaints are one of the most important metrics in email marketing. They quietly determine whether your emails reach inboxes or disappear into spam folders. So, start tracking your emails today and stop getting your emails marked as spam.