Spam Complaint Rate

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Spam Complaint Rates are between 0% to 100%; once you finish the equation, turn your answer to a percentage by multiplying by 100.

Actions contributing to your spam complaint rates occur when a recipient clicks on the “This is Spam” (TiS) button in their email client. If the Mailbox Provider (MBP) has a feedback loop (FBL) in place, the sender will be notified of the action taken by the recipient. 

Tips for interpreting Spam Complaint Rates:

Spam complaint rates are meant to show the fraction (or percentage) of people that clicked the TiS button — however, note that not all MBPs offer an FBL. (For more on this see, “List of all available complaint feedback loops”) When you are looking at Spam Complaint Rates, remember that the reported number of complaints could look artificially low if you send to destinations (such as Gmail) not offering an FBL. For this reason, spam complaint rates are often more powerful to compare across emails over time, rather than to use on their own. 

In general, the LOWER the spam complaint rate, the better. However, low spam complaint rates don’t fully tell the story of the success of an email and can actually be a sign of a deliverability issue since recipients are not able to mark emails as spam if they are already in their spam folder.

Spam complaints are heavily weighted by MBPs since they are a clear indication that the mail is not wanted. High spam complaint rates should be investigated and dealt with quickly to avoid damaging sender’s reputation and your ability to hit the inbox consistently. 

Quick tip: just like spam complaints can be very damaging to sender reputation, any “this is not spam” (TiNS) reports coming from your recipients who find messages in their spam folder can greatly improve your ability to hit the inbox. 

See our other articles for examples of negative engagement metrics that aren’t as susceptible to under-reporting, like the Unsubscribe Rate. 

Use spam complaint rates to help optimize your email campaigns by:

  • Identifying content that recipients have advised they do not wish to receive
  • Detecting problems with list collection, targeting, and/or unsubscribe process
  • Evaluating the performance of an email program over time

Related Links:

Looking for guidance on how to deal with spam complaints? Check out M3AAWG Recommendations for Senders Handling of Complaints

Curious when spam complaint rates start to affect inbox placement? Check out Email Deliverability Unfiltered: All About Email Metrics

Not convinced about why the spam complaint rate is an important metric to monitor? Check out Marketing Metrics: When A Negative Can Become A Positive.

Need some help reducing your spam complaint rate? Check out 9 Tips to Reduce Your Email Marketing Complaint Rate