Spam Complaints: Cause, Effect, and Cure

What are Spam Complaints, and How Can You Keep Them From Happening?

Spam complaints are negative responses to an email. They are specific actions taken by the receiver of the email to let the ISP, ESP, or sender know he’s not happy about the email and wants to report it as spam.

Although it’s almost inevitable that your email will generate some spam complaints, high complaint rates are indicative of a problem and cause poor Inbox delivery.

Spam complaints are a key driver of email deliverability, so it’s important to understand them.

Complaints generally take two different forms:

1) “This is Spam” report

The most common type of complaint is when the email recipient reports a message as spam by clicking on the “This is Spam” or “Report as Spam” button (or equivalent) from within their web-based email application, such as those provided by Hotmail (now Outlook), Gmail and Yahoo.

When this button is clicked, most ISPs or email providers report that action, along with a copy of the email message, back to the sender via what’s known as an email feedback loop. This feedback loop process allows the sender to unsubscribe that address.

Gmail has a spam button but does not provide a feedback loop. They instead utilize an unsubscribe header that gives a subscriber that clicks on the complaint button the option of unsubscribing or reporting the message as spam. If the subscriber chooses to unsubscribe, this information is passed back to the sender.

Most ESPs and list management software automatically remove a subscriber’s email address that is received via feedback loop or Gmail’s unsubscribe function.

2) Manual complaint to an abuse desk

A more serious form of complaint is when the email recipient forwards the email to the abuse desk at the ISP, ESP, or sender along with a personal note saying they consider the email to be spam. This is considered a more significant form of a complaint since it takes more work by the recipient to report this type of abuse—more than just the click of a button. When the subscriber takes this action to report an email, the email addresses for these types of complaints are generally not automatically unsubscribed when they’re received. Additional action by the sender is required to manually unsubscribe or remove that email address from future sends.

If you see a manual complaint to an abuse desk, you should reply back to the reporter and investigate how the subscriber got on the list and any other details you can find. You may be able to find and fix a problem with your email campaigns before you’re blocked.

How do they happen? Why do recipients mark a message as a spam complaint?

Recipients may mark your email as spam if it’s:

  • Not Requested – Perhaps the most common reason for a complaint is that the email was not requested in the first place.
  • Not Recognized – The recipient doesn’t recognize the email as something they subscribed to.
  • Too Frequent – Mail that is sent too frequently will likely annoy subscribers and cause them to click on the spam button.
  • Not Frequent Enough – The recipient may not remember signing up for your emails if the mail is sent infrequently or sporadically.
  • Not Relevant – Sending email that is not relevant to the subscriber or content that is different from what the subscriber agreed to receive when they signed up. Recipients that are interested in what you send will complain far less often.
  • Received after unsubscribing – CAN-SPAM laws allow for up to 10 days to remove a subscriber after an unsubscribe request is made. Still, if recipients continue to get emails after unsubscribing, they are likely to mark the message as spam. Remove these unsubscribed addresses ASAP. Most ESPs and mailing list software does this automatically and immediately if received via an unsubscribe link, but be sure to process all unsubscribe requests received through other channels. Speaking of other channels – be sure to provide other options for unsubscribing in case the unsubscribe link does not work.
  • Just not wanted anymore – Some recipients may just click “This is Spam” as a way to unsubscribe. You can limit this by making your unsubscribe link obvious and making sure the process to unsubscribe is easy.
  • Or, a recipient may just highlight several messages in the Inbox all at once and click on the spam button to remove them. Your message may be unintentionally highlighted in this process. By prominently branding your “From name” you can help prevent this from happening.

Know how your complaint rate is calculated

A benefit of receiving the feedback loop data that results from a subscriber clicking the spam button is that this information can be used for reporting purposes. The number of complaints received can be tracked and used to calculate your complaint rate. The complaint rate is calculated as follows:

Overall spam complaint rate formula

There are two important nuances in calculating your spam complaint rate that both deal with the definition of “Total Emails Delivered.”

The first issue is whether the “Total Emails Delivered” includes either:

  • Messages placed in the Inbox, which we call the “Inbox spam complaint ratio.”
  • Both messages placed in the Inbox and the Bulk folder, which we call the “messages sent spam complaint ratio.” This is calculated by taking the messages sent and subtracting bounces.

ISPs use the “Inbox spam complaint ratio” because this best shows how wanted your email is by your recipients, and most information on acceptable complaint ratios is referring to the “Inbox complaint ratio.”

The problem is that only the ISPs know the actual number of messages that were placed in the Inbox, so your software or ESP is showing you a “messages sent spam complaint ratio.”

If you don’t have much email going to the Bulk folder, then these numbers will be similar, but if you have significant email going to the Bulk folder, this will reduce the complaint ratio that you see.

As an example, 100,000 messages are sent, and of those, 20,000 are placed in the Inbox, and 80,000 are placed in the Bulk folder. Of the 20,000 placed in the Inbox, there are 100 complaints. Therefore, the “Inbox spam complaint ratio” is 100 divided by 20,000 = 0.5%. The “message sent spam complaint ratio” is 100 divided by 100,000 = 0.1%. Your software or ESP will probably show you 0.1% (which would be a slightly high but acceptable “Inbox spam complaint ratio”), but the ISP sees 0.5% (which is a very bad “Inbox spam complaint ratio”).

It’s important to remember that if you have significant email going to the Bulk folder, the spam complaint ratio you see in your software will be significantly lower than the actual “Inbox spam complaint ratio” that the ISPs see.

Your “Inbox spam complaint ratio” is always equal to or higher than the “messages sent spam complaint ratio” that you see.

The second issue is: If the denominator (total emails delivered) includes mail sent to domains without feedback loops (FBLs), your calculated complaint rate doesn’t include complaints reported to those domains. If, for example, 50% of your email volume is sent to ISPs without FBLs (a reasonable estimate), then assuming the number of complaints is similar across all domains, the calculated complaint rate would be only half of the actual rate.

It is also best to calculate the complaint rate by each individual ISP that provides feedback loop data, rather than the overall rate, since the complaint rate at some ISPs may be low while others may be high, thus skewing the results.

Monitor your complaint rate

A consistently high complaint rate can definitely hurt your sending reputation and affect Inbox delivery. Look at your spam complaint rate for each mailing, and also track it over time to see trends. Are there just spikes in the rate for certain types of mailings, or is it getting higher with each mailing? If your Inbox spam complaint rate goes above 0.1%, that is, one per thousand emails delivered, you should review your entire email process from address collection all the way through to the campaign being sent.

Then, review your mailing practices

Take these actions to reduce spam complaints, but remember that consistently following best practices is the best way to prevent the causes (and effects) of high complaint rates.

  • Make sure your mail was really requested — Start by reviewing your email address collection process. Receiving clear permission to send emails is critical.
  • Get the frequency right by setting proper expectations upfront — Be clear on what you send and how often you will send it. Allow your subscribers to create new permissions by offering a preference center where the subscribers can sign up for more or less frequent emails or different subjects they are interested in.
  • Be familiar and recognizable — Send an automated welcome letter within 24 hours to acknowledge the subscription and help to establish a relationship with your new subscriber.
  • And use consistent branding – Use the same “From name” and “From email address” on each mailing. If possible, your campaigns should use the same look and feel as the website where the permission was granted. This allows the recipient to recognize you at a glance and recall and associate your brand with the signup process they went through.
  • Prominently display an unsubscribe link at the top of your message or in the pre-header — This may seem counter-intuitive, but if a subscriber is looking for a way out of receiving your messages, they will use the easiest way to do it. Make the unsubscribe process easier than marking it as spam. Once this request is made, process the unsubscribe request immediately.
  • Keep your ongoing emails relevant and engaging — Offer incentives to click on your links, even if that click would not directly lead to a sale. Clicks show engagement, engagement shows interest, and interest maintains recognition in your email and helps prevent a spam complaint.
  • List Maintenance — Implement an automated, ongoing process to remove or suppress old and inactive subscribers. Subscribers who are not engaging are not adding to your bottom line and are much more likely to report your messages as spam. Older and non-engaged addresses may have also been converted into spam traps.

Unfortunately, even marketers using the very best mailing practices see some spam complaints. Fortunately, the ISPs recognize this inevitable fact and take it into account. They want good, requested mail to reach their subscribers’ Inboxes and spam to stay out, and do their best to identify both correctly.

Tracking your spam complaint rate and following these recommendations will help you keep your complaint rates low, your engagement high, and greatly increase the chances of your messages reaching the Inbox.


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