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Is feedback loop information considered public domain?

Michael Ko profile picture
Michael Ko
Co-founder & CEO, Suped
Published 11 Aug 2025
Updated 17 Aug 2025
8 min read
The world of email deliverability often involves navigating various data points, some publicly accessible and others strictly confidential. A common question that arises is whether feedback loop (FBL) information, which is critical for managing email sender reputation, is considered public domain. Understanding this distinction is vital for anyone sending emails, from marketing professionals to system administrators, to ensure compliance and maintain good standing with mailbox providers.
Feedback loops are a cornerstone of effective email management. They provide senders with reports on recipient complaints, allowing them to remove disengaged or annoyed subscribers from their mailing lists. But what about the data itself? Is it something anyone can access, or is it protected information?

What are feedback loops and why are they important?

To properly address the question of FBL data and the public domain, we first need to clarify what feedback loops are and how they operate. Feedback loops are mechanisms provided by Internet Service Providers (ISPs) and mailbox providers that allow legitimate bulk email senders to receive reports of spam complaints from their subscribers.
When a recipient marks an email as spam or junk, the FBL system notifies the sender, typically through an Abuse Reporting Format (ARF) report. This report contains information about the complaint, such as the original email headers, which can help the sender identify the specific email that triggered the complaint and, crucially, the subscriber who complained (though often anonymized to protect privacy). This process is crucial for maintaining a healthy sender reputation, as excessive complaints can lead to emails being blocked or landing in the spam folder.
  1. Purpose: FBLs exist to help senders understand and react to recipient complaints, ultimately improving overall email deliverability. They are a critical component for email marketers to maintain positive standing with mailbox providers.
  2. Providers: Many major providers offer FBLs, including google.com logoGoogle (Gmail) and yahoo.com logoYahoo Mail. Each provider may have slightly different requirements for enrollment and data presentation. You can learn more about which inbox providers offer feedback loops.
Without FBLs, senders would largely be blind to user complaints, leading to a build-up of negative sentiment that could severely damage their sender reputation and potentially land them on an email blacklist (or blocklist).

Understanding the concept of public domain

The term "public domain" in the context of intellectual property (IP) laws refers to creative works and information that are not protected by copyright, patent, or trademark laws. This means anyone can use, reproduce, or distribute such materials without needing permission or paying royalties.
Works typically enter the public domain when their copyright expires, or if they were never eligible for protection in the first place, such as certain government documents in the U.S. As Stanford University's Fair Use Project explains, "Public domain refers to creative materials not protected by IP laws."
Crucially, raw data and factual information, while they might be derived from copyrighted works, are generally not subject to copyright themselves. However, the way that data is presented or organized can be copyrighted. This distinction is important when considering FBL information.
Understanding Public Domain
  1. No copyright: Materials in the public domain are free for anyone to use without permission.
  2. Expiration: Works enter the public domain after their copyright term expires, or if they were created before copyright laws existed.
  3. Ineligibility: Some types of works, like raw facts or ideas, are not eligible for copyright protection.

Is FBL information typically public?

No, feedback loop information, particularly the granular details provided to senders, is generally not considered public domain. While the existence of FBL programs is public knowledge, the specific data shared through these loops is confidential and proprietary. Mailbox providers collect and share this data under strict terms of service and confidentiality agreements with the senders who enroll.
The primary reason for this confidentiality is privacy. FBL reports often contain encoded identifiers that allow senders to link a complaint back to a specific subscriber, even if the subscriber's direct email address isn't explicitly provided. Releasing such information into the public domain would be a significant privacy violation and could lead to misuse, undermining the very purpose of FBLs as a tool for responsible sending.
Mailbox providers have a vested interest in keeping this data private. It protects their users' privacy and maintains trust in their email systems. If FBL data were public, it could be exploited by malicious actors, leading to more spam or abuse, which is precisely what FBLs are designed to combat. The data is shared to help senders improve, not to be broadly disseminated.

Typically Shared with Senders (Confidential)

  1. Aggregated Spam Rates: Overall complaint percentages for your sending domains or IPs, often seen in Postmaster Tools.
  2. Complaint Source: Information identifying which campaign or message led to a complaint, via the FBL identifier.
  3. Anonymized User IDs: Encrypted or hashed data linking to the specific subscriber who complained, but not their direct email.
  4. Original Email Headers: Portions of the email to help identify the problematic message.

Generally Not Publicly Available

  1. Individual User Identifiable Data: Direct email addresses, names, or other personal details of complainers.
  2. Raw FBL Feeds: Unfiltered streams of complaint data from all senders or for all mailbox providers.
  3. ISP Internal Metrics: Proprietary algorithms or detailed internal reports used by ISPs to process FBLs.

Data access and usage policies

Mailbox providers have explicit policies governing how FBL data is accessed and used. When a sender enrolls in an FBL program (like Google's FBL or Oath's FBL), they agree to terms that dictate how the complaint data can be handled. These terms almost universally stipulate that the data is for internal use only, specifically for managing subscriber lists and improving sending practices, and cannot be shared publicly.
Furthermore, many FBL providers (including a Universal Feedback Loop often associated with Validity) employ anonymization techniques or offer data via a user interface rather than a raw, exportable format that could easily become public. This ensures that while senders get the actionable insights they need, the underlying personal data remains protected. Cornell University's Copyright Information Center emphasizes that a work is in the public domain if its copyright term is over, or if the creator has designated it as such. FBL data is explicitly neither of these. It's confidential data under specific licensing terms.
The confidentiality also extends to the specific details about a sender's performance. For example, knowing another company's exact spam complaint rates or how many times their emails are marked as spam would be valuable competitive intelligence. Mailbox providers protect this information as well, as it is proprietary to the sender and the provider.

Important Note on FBL Data Sharing

While mailbox provider partners may have access to sender subscriber information via a user interface within a Universal Feedback Loop (uFBL) platform, this data is not typically available through a general export function. This design choice reinforces the non-public nature of FBL data and helps safeguard privacy. The goal is to provide actionable intelligence to senders, not to make individual user data broadly distributable.

Implications for senders

For email senders, the non-public nature of FBL information has significant implications. It means you can rely on this data as a private, actionable tool to refine your sending practices without fear of your detailed complaint metrics being exposed to competitors or the general public.
The primary benefit of FBLs is their ability to help you quickly identify and remove subscribers who are actively complaining. By promptly removing these users, you reduce your complaint rates, which in turn improves your domain reputation and overall email deliverability. Ignoring FBLs or failing to act on the data they provide is a common reason why emails end up in the spam folder (or junk folder).
Therefore, while the information isn't public, its impact on your public sender reputation is very real. Responsible senders diligently monitor their FBL data and use it to maintain healthy lists and ensure their emails reach the inbox effectively.

Views from the trenches

Best practices
Monitor FBLs regularly to identify and promptly remove complainers from your mailing lists, enhancing sender reputation.
Segment your email campaigns using unique FBL identifiers to pinpoint which content or audience segments are generating the most spam complaints.
Ensure your email platform or ESP is properly configured to receive and process FBL reports efficiently, automating suppression where possible.
Understand the terms of service for each FBL you enroll in to ensure compliance with data usage and privacy policies.
Maintain high engagement rates to naturally reduce complaint rates, as engaged subscribers are less likely to mark emails as spam.
Common pitfalls
Assuming FBL data is public domain, leading to inappropriate sharing or misuse of sensitive complaint information.
Failing to act on FBL reports quickly, allowing high complaint rates to persist and negatively impact deliverability.
Not implementing proper opt-in processes, which increases the likelihood of complaints and FBL triggers.
Overlooking the nuances of different FBL providers, as each may have unique reporting formats or data handling policies.
Neglecting to integrate FBL data with your CRM or marketing automation platform for automated suppression.
Expert tips
Consider FBL data as proprietary and confidential, handling it with the same care as other sensitive customer information.
Leverage the specific details within FBL reports, even anonymized ones, to identify problematic email content or list segments.
Proactively clean your mailing lists to remove inactive or unengaged subscribers before they become complainers.
Use FBL data to refine your content strategy, ensuring it aligns with subscriber expectations and reduces potential friction.
Regularly review your sender reputation dashboards from providers like Google and Yahoo to correlate FBL data with overall domain health.
Expert view
Expert from Email Geeks says that FBL information, including company names and addresses provided to ISPs, is not public domain. While some data might implicitly leak, it's generally considered proprietary and should not be treated as public.
2024-05-15 - Email Geeks
Marketer view
Marketer from Email Geeks says that FBL data does not become public domain. While the question of how much information might inadvertently leak is a separate issue, it is generally believed that FBL data remains confidential.
2024-05-15 - Email Geeks

Summary

In conclusion, while the concept of public domain applies to many forms of information, feedback loop data falls outside of this definition. It is proprietary and confidential information shared between mailbox providers and legitimate email senders under specific terms designed to protect user privacy and combat spam.
For email marketers and deliverability professionals, this means you can utilize FBL reports as a trusted, private resource to identify and address spam complaints. Acting promptly on this data is essential for maintaining a strong sender reputation and ensuring your emails consistently reach the inbox.

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