Understanding and Monitoring the Spam Complaints Rate

A practical guide to understanding, tracking, and responding to spam complaints

Spam complaints are signals sent by email recipients indicating they no longer want to receive messages from you—typically by clicking the 'Report Spam' button in their inbox.

For mailbox providers, this is a clear indication that the content may be unwanted or misaligned with user expectations.

Note: Spam complaints are one of the worst forms of feedback you can receive from your subscribers. They put your sender reputation at serious risk.

Why is the Spam Complaints Rate a Key Metric?

Mailbox providers carefully monitor spam complaints rates:

• Since June 2024, Google and Yahoo introduced new requirements.

• As of April 2025, others such as Microsoft and Orange have followed suit. These rules apply to all bulk senders (those sending over 5,000 marketing emails per day).

Exceeding the 0.3% threshold is considered a policy violation and can negatively affect your sender reputation and email deliverability.

How to Keep Track of & Interpret Spam Complaints?

→ Monitoring Spam Complaints in Batch

Batch allows you to monitor spam complaints at the campaign level.

• Orange indicator: Threshold exceeded

• Red indicator: Spam complaints rate has reached an abusive level

Even if the spam rate drops, that does not always mean everything is fine. A few complaints may still indicate irritation among your audience.

• No complaints at all? That might be a red flag—your emails could be landing in the spam folder, or the provider may not be reporting complaints.

• Not all mailbox providers share information on complaints: The spam complaints rate is an indicative metric shown only when mailbox providers share feedback loop data. Batch currently receives feedback from Yahoo, Microsoft, major French mailbox providers (Orange, Free, SFR, La Poste), and others. For French domains, data availability depends on subscriber consent.

→ Benchmark

• Best practice: Below 0.1%

• Warning sign: Above 0.1%

• ⚠️ Serious issue: Above 0.3% (likely related to list quality or message content)

How to Interpret Your Spam Rates?

Interpreting the volume of spam complaints for your subdomains is not an easy task. Here a several things you need to know to interpret correctly your results:

→ Not All Email Services Offer Feedback Loops (FBLs)

Only some email providers (e.g., Microsoft - Hotmail/Outlook, Yahoo, Comcast, etc.) offer FBLs that notify ESPs when an email is marked as spam. Gmail, for instance, does not provide individual complaint data—only general trends via Google Postmaster Tools.

→ Spam Complaint Data Doesn't Tell the Full Story

Some mailbox providers only share spam complaint feedback if:

• The spam complaint report is made from their dedicated webmail interface or their own mobile app (e.g. not from a third-party email client)

• And if the user who complained agreed to share the spam report with third-parties like Batch.

As a consequence, the volume of spam complaints you see on Batch dashboard is just a fraction of all spam complaints generated by your emails. This is the case for some European mailbox providers like Orange. Only about 10% of subscribers consent to share complaint data.

Tip: Multiply complaints rates by a factor of 5 to 10 for such providers to estimate actual figures.

→ Users May Delete Messages Instead Of Marking As Spam

Some recipients simply delete emails they do not want. These are still negative signals, even if they are not reflected in spam complaint stats.

→ Spam Filters May Categorize Messages As Spam

If your message goes directly to the spam folder, users will not see it and cannot mark it as spam—even if it is. Only messages that land in the inbox and are flagged manually generate spam complaints.

How to Troubleshoot Spam Complaints issues?

We have prepared a step-by-step guide to help you find the campaigns & automations potentially harming your sender reputation: Troubleshooting spam complaints issues