Step-by-Step Guide of Feedback Loops for Email Receivers cover


Step-by-Step Guide of Feedback Loops for Email Receivers

Email communication is more crucial now than ever, and managing spam effectively is important for maintaining operational efficiency and user satisfaction. This is where Spam Complaint Feedback Loops (FBLs) play a transformative role. Complaint Feedback Loops (or FBLs) allow you or your users to send spam complaints back to the message's originator for them to take action. FBLs enable swift action against spam outbreaks, reduce the burden on your support desk, and enhance overall email hygiene. By understanding and implementing FBLs, you can turn the tide against spam, leading to less blockage of legitimate emails, happier users, and reduced support hassles.

Why Should You Encourage Spam Complaints?

Senders are quickly alerted to spam outbreaks on their networks, reducing the amount of spam you receive and the amount of time and resources required to handle it.

The number of spam complaints sent by your end-users to your support desk will therefore be reduced, and these users will recognize that providing feedback decreases the amount of spam they receive, so will be willing to provide further feedback.

This ultimately leads to less blocking of legitimate mail, happier users and less support.

If you receive mail, then you typically send it too, so you can benefit from FBL reports too. They will help you to quickly identify compromised, infected or malicious accounts or accounts with bad address collection and sending practices, so you can maintain your reputation and avoid blocklists.

How Does It Work?

Abusix provides a free FBL reporting service that takes in your feedback reports, does the necessary encapsulation, checks the trustworthiness of the sender and then generates and sends the report to the Sender.

The sender then remediates the issue, or, their reputation decreases over time to the point where their mail is blocked.

All you need to do is set-up the “This is Spam” button in your mail platform to forward the feedback messages to an email address that we will provide to you and we’ll take care of everything else. This can be done in minutes.


Complaint Feedback Loops have been in use by many mailbox providers since the mid to late 2000s and were driven by Return-Path, who provided a “Universal Feedback Loop” service.

This required senders to opt in, register their sending IP ranges, and go through a vetting process. Whilst for the receivers, they simply sign up and forward their reports for processing and onward reporting.

It was provided for free to both receivers and senders but had some limitations; not everyone could use the service, and you had to be sufficiently “large” enough to warrant the time to set up.

Last year, with Return-Path having been acquired by Validity, announced they were going to charge the senders based on their sending volume to continue receiving these reports.

This was obviously bad for the email community at large and thereby started the process of creating a standard way for Feedback Loops to operate without having a centralized entity in control of the process.

This led to the publication and approval of RFC 9477 along with another Internet Draft which allows senders to specify to receivers where feedback loop reports should be sent, linked to a DKIM signature applied to the message which provides security and reputation via authentication. This allows any receiver to implement a feedback loop without any intermediary if desired.

The drawback is that this whole process will take time for both parties to implement.

This is where Abusix comes in. Our ethos is to report, prevent, and handle internet abuse at scale. We already have an infrastructure for reporting abuse, and we already have an email blocklist and reputation product.

We have also modified our reporting platform to handle Complaint Feedback Loops and integrate our Mail Intelligence reputation data to determine automatically if a sender is trustworthy enough to receive a feedback loop report.

All a receiver needs to do is to send us their complaint reports and we will report them back to any senders that have implemented either RFC 9477 or the Internet Draft.

If you’re already reporting Feedback Loop data to Validity, then you can report it to us at the same time without issue, worst case is that the sender receives two reports.


As a receiver, to send us Feedback Loop data is simple and can be done in just a few minutes:

1) Create an account at and log in.

2) On the left-hand navigation under “Platform Functions,” click “Data Channels.”

3) Click “Create a Data Channel.”

4) Select “Report Abusive Behaviour” and click “Next.”:

5) Select “Send data using SMTP forward” and click “Next.”:

6) Name your data channel something appropriate like “Feedback Loop,” select the “Mail from a spam inbox” option, and then click “Next.”:

7) Agree to the terms of service and click “Next”:

8) Configuration of your endpoint is complete, and you are provided an SMTP address to send your user feedback.

9) Lastly, configure your mail system to use the supplied SMTP address as the destination for your “This is Spam” feedback, then email us at [email protected] to let us know that the Data Channel you have set up is for Feedback Loop reporting, as we will have to enable your Data Channel for this purpose.

Once this is done, we’ll start reporting your feedback loop data for you immediately.

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