Feedback loops can affect your sender reputation and impact your entire email program

Email Feedback Loops

Maintaining a clean list and good sender reputation are critical if you depend on email to help drive revenue (and who doesn’t these days?). Doing so, however, isn’t easy. It requires constant vigilance. Thankfully, email marketers have a variety of data at their disposal to help them maintain a clean list and ensure a good sender reputation. One source of that data is email feedback loops.

What is an email feedback loop? An email feedback loop is a report that ISPs send to large-volume senders for every email recipient who marked the sender’s message as spam, also known as a complaint. Future messages can be suppressed, preventing unwanted messages in a recipient’s inbox. When recipients receive your email message, they have several options: they can delete it, read it, or mark it as spam. Because the ISP keeps track of how many recipients mark your messages as spam and uses the received-to-complaint ratio to gauge a sender’s reputation, it’s important to subscribe to feedback loops and use this data to consistently clean your list from recipients that don’t want your messages, keeping that ratio positive rather than negative (more on that in our next post).

Managing feedback loops can be a challenge. First of all, not all ISPs provide them. Of those that do provide feedback loops, there can be hundreds or thousands of domains that fall under that ISP; you don’t just subscribe to a feedback loop for Hotmail, for example, but all the domains that fall under as well (such as or

SparkPost makes the process of subscribing to and processing feedback loops easier for senders. Senders subscribe to most feedback loops on an IP basis. Anytime SparkPost puts an IP into production, we automatically subscribe to all the feedback loops on the sender’s behalf – even for a dedicated IP.

If you’d like to get a rough idea of your reputation, you can look up your sending IP, domain, or both at, and the site will provide your sender score. This includes your FBL rate, among other reputation measures. The site is managed by Return Path, a company that handles feedback loop processing for a number of ISPs. While they have a couple of large and many smaller ISPs as their customers, Return Path doesn’t process feedback loops for every ISP. It’s important to note, therefore, that the sender score they provide is based on the feedback loops they process, so it’s not 100% accurate, but can give you an idea of where you stand.

In all of this, bear in mind that feedback loops are a negative statistic – a recipient doesn’t want your message so much that they clicked the spam button rather than deleting it and moving on. You’re really looking for positive statistics, which indicate engagement. That means following the best practices of good list hygiene, removing anyone who hasn’t opened or clicked on your message in a certain timeframe. If you send to a subscriber multiple times in a week, look at 30 days opened or clicked stats and if anybody hasn’t opened or clicked longer than that, send to them less frequently or try to engage them in a different way. If you send weekly, you might look at 90 days, or if you send monthly, look at six months’ worth. The key is never to send to any subscriber who has not opened or clicked actively in the past 12 months as you run the risk of hitting inactive email addresses that have been turned into spam traps. Even when the address is still good, these recipients are clearly showing you they are not interested in your mail, and are much more likely to click the spam button and harm your inbox placement as a result.

Work toward strong engagement with your subscribers, making sure that the people you send to really want your messages. If you do that, you will be able to keep your sender reputation—and your email marketing efforts—strong.

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