The Truth About Spam Complaints

Brad Gurley, Senior Director of Deliverability, Real Magnet  


These three words almost instantly strike fear into the hearts of most email marketers. It’s probably your worst nightmare to have your recipients click the Spam button – but not all senders know what that really means. Much like popular urban legends, the truth about spam complaints is often shrouded in misinformation and incorrect interpretations. Today, we’re going to confront your worst spam button fears and set the record straight on exactly what spam complaints mean for you.

What is a spam complaint?

We often hear confusion regarding what actually constitutes a spam complaint. The likely reason is that there are a several correct answers. A spam complaint is typically recorded when a recipient:

  • Clicks a button in their email client indicating the message is spam, bulk, or otherwise unwanted
  • Forwards the email to the sender’s abuse team, email service provider, or hosting company

In the first instance, the spam complaint is recorded by the mailbox provider (like Google or Microsoft) and included in the metrics they use to filter incoming mail. In some cases, the mailbox provider will also send the complaint to your ESP or web host, and in severe or repeated cases these can lead to the provider taking action against your account.

This forwarding of the complaint to your ESP is part of a feedback loop (FBL). The “spam complaints” metric you see in Real Magnet and other ESP reporting refers to complaints received via FBL. Because some mail providers consider forwarding the complaint details to be a violation of user privacy, not all providers participate in FBLs. Google is the most prominent example of a mailbox provider that does not return individual complaint data via FBL.

Other actions that are often considered spam complaints include moving a message to the Spam or Junk folder, informing an IT team about an unwanted message or sender, or reporting to a government agency (such as the FTC in the US or CRTC in Canada). These actions are not likely to show up in reporting from your ESP, but can still contribute to mail being rejected or even regulatory actions and fines.

Why do complaints matter?

If you send mail for your organization, spam complaints should always be on your radar. Receiving too many spam complaints from a specific mailbox provider can cause your mail to be routed to the spam folder for that provider’s users. Even worse, it can cause you to be blocked by a specific ISP or even a third-party blacklist that can cause delivery problems at multiple providers. If your mail is being routed to the spam folder, you often won’t even realize it unless you see a dip in opens or engagement from your recipients.

Even before spam complaints cause you to be blocked or routed to spam, they can serve as a valuable warning sign that something is wrong with your mail program. Too many complaints can indicate problems with your contact acquisition process, mailing frequency, or message content.

What should my spam complaint rate be?

Much like bounces, the ideal number of spam complaints is zero. And for senders who follow all best practices, your rates are likely to be very close to that. In years past, industry sources often quoted complaint rates for all the major providers, typically in the range of 0.001% to 0.01%. However, as spam filtering has advanced, these thresholds mean very little. In most cases, spam complaint rates are just one of dozens of metrics that determine whether your mail makes it to the inbox. The goal remains to keep spam complaints as low as possible. If you need a metric to shoot for, aim for less than 0.001%.

When looking at these metrics a couple of things should be kept in mind. First, if your mail is already going to the spam folder, your complaint rates will be very low. You typically won’t receive spam complaints for mail that is already in the spam folder. In addition, remember that Gmail – typically one of the largest components of any recipient list – doesn’t return individual complaint data, along with a handful of other providers and most corporate domains. As a result, there’s a good chance your complaint rate may be noticeably higher than what is recorded by your ESP metrics.

What should I do now?

In years past, it was possible to achieve pretty high inbox delivery by monitoring or even manipulating a few key metrics – complaints, bounces, and opens, for example – without a lot of additional effort. In today’s email landscape, mailbox providers take a much more holistic view of inbound email streams. Monitoring these metrics remains important, but primarily as indicators of the overall health of your email program. If these numbers are not ideal, you’ll need to find and correct the root cause of the problem instead of simply addressing the symptoms.

Develop a detailed plan on how to protect your sender reputation by mitigating spam complaints. To learn more, watch our webinar, “Protect Your Sender Reputation: Tips & Trends to Avoid Deliverability Pitfalls.