How do email service providers process feedback loop (FBL) emails to identify users and manage suppressions?

Summary

Email Service Providers (ESPs) process Feedback Loop (FBL) emails, reports from ISPs about spam complaints, to identify users who mark messages as spam and suppress them. This involves receiving reports, often in ARF format, parsing them to extract user information using unique identifiers embedded in email headers or custom headers, and automating suppression. Most ESPs build custom FBL processing systems. Actively managing FBLs lowers spam rates, improves reputation, and ensures deliverability. Monitoring and prompt suppression are crucial, as high complaint rates negatively impact deliverability.

Key findings

  • FBL Crucial: Handling FBLs is crucial for maintaining sender reputation and improving deliverability.
  • Unique Identifiers: Identifying users typically relies on unique identifiers embedded in headers.
  • ARF Format: FBL reports often conform to the Abuse Reporting Format (ARF).
  • Automated Systems: ESPs commonly use automated systems to process FBLs and update suppression lists.
  • Custom Systems: Most places build their own FBL processing systems.

Key considerations

  • System Development: Consider building a custom FBL processing system for control and reporting.
  • Identifier Embedding: Ensure each email has a unique identifier in the headers.
  • Hashing: Consider hashing recipient addresses.
  • Prompt Suppression: Implement systems to promptly suppress complaining users.
  • FBL Monitoring: Implement a system for monitoring and processing FBLs

What email marketers say
10Marketer opinions

Email Service Providers (ESPs) process Feedback Loop (FBL) emails to identify users who mark messages as spam and then suppress them from future mailings to maintain a good sender reputation and improve deliverability. This involves receiving Abuse Reporting Format (ARF) reports from Internet Service Providers (ISPs), parsing these reports to extract user information, often using unique identifiers embedded in email headers or custom headers. Once identified, the user is automatically unsubscribed and added to a suppression list. Many ESPs recommend building custom FBL processing systems for better control and reporting. Actively managing FBLs and suppressing complaining users helps lower spam rates, improve reputation with ISPs, and ensure emails reach subscribers' inboxes.

Key opinions

  • FBL Importance: Handling FBLs is crucial for maintaining sender reputation and improving deliverability.
  • Identification Methods: Identifying users from FBL reports typically involves unique identifiers embedded in email headers or custom headers.
  • Automated Processing: ESPs commonly use automated systems to process FBL reports and update suppression lists.
  • Benefits of FBLs: Actively managing FBLs leads to lower spam rates, improved reputation with ISPs, and better inbox placement.
  • ARF format: FBL reports often conform to the ARF format.

Key considerations

  • Custom Systems: Consider building a custom FBL processing system for better control and reporting capabilities.
  • Dedicated Addresses: Set up dedicated email addresses for receiving FBL reports for easier management.
  • Prompt Suppression: Implement systems to promptly suppress users who generate spam complaints to prevent further issues.
  • Unique Identifiers: Ensuring each email has a unique identifier helps match the email to a recipient for suppression
Marketer view

Email marketer from Reddit explains that FBLs are processed by first receiving the ARF report, then using unique identifiers (like custom headers) to match the complaint to a specific user. Finally, the user is automatically unsubscribed.

May 2022 - Reddit
Marketer view

Email marketer from Litmus discusses the importance of FBLs by highlighting that they are a direct line to understanding subscriber complaints. Proper processing and suppression improve sender reputation and deliverability.

November 2023 - Litmus
Marketer view

Email marketer from StackOverflow shares that they use a combination of custom headers and database lookups to identify users from FBL reports. Once identified, an automated script unsubscribes the user and records the complaint.

May 2021 - StackOverflow
Marketer view

Email marketer from SendGrid shares that automated FBL handling involves receiving reports from ISPs, parsing the ARF format to extract user details, and updating the suppression list via API calls.

March 2022 - SendGrid
Marketer view

Email marketer from Email on Acid Blog discusses that FBL strategies involve setting up dedicated email addresses for FBL reports and using automated systems to process these reports. Identifying users typically relies on unique identifiers embedded in the email headers.

March 2024 - Email on Acid Blog
Marketer view

Email marketer from MXToolbox discusses that actively managing FBLs and promptly suppressing users who complain lowers spam rates. This improves your reputation to ISPs, ensuring your emails reach subscribers’ inboxes.

June 2021 - MXToolbox
Marketer view

Email marketer from Email Geeks shares that they normally have ways to identify users and campaigns to update statistics and put the contact in the suppression list.

May 2022 - Email Geeks
Marketer view

Email marketer from Mailjet Blog shares that handling FBLs is crucial for maintaining a good sender reputation. ESPs should automatically process FBL reports, identify complaining users, and remove them from active mailing lists to prevent future spam complaints.

December 2022 - Mailjet Blog
Marketer view

Email marketer from Email Geeks recommends building your own FBL processing system for easier maintenance and custom reporting.

October 2021 - Email Geeks
Marketer view

Email marketer from Email Geeks shares that most ESPs will utilize other headers to identify the contacts to suppress.

July 2023 - Email Geeks

What the experts say
4Expert opinions

Email service providers (ESPs) process Feedback Loop (FBL) emails by encoding or hashing recipient addresses or embedding unique identifiers in email headers, allowing them to correlate abuse reports with specific users and automate suppression. Most ESPs develop their own FBL processing systems to manage these reports efficiently.

Key opinions

  • Encoding/Hashing: ESPs often encode or hash recipient addresses in headers for identification.
  • Unique Identifiers: Using unique identifiers is key to correlating reports with users.
  • Custom Systems: Most ESPs build their own FBL processing systems.
  • Automated Suppression: FBL processing enables automated unsubscription of complainers.

Key considerations

  • Identifier Embedding: Ensure emails contain unique identifiers in headers.
  • Hashing: Consider hashing recipient addresses.
  • System Development: Plan to develop or adapt an FBL processing system.
Expert view

Expert from Word to the Wise explains that processing FBLs involves ESPs using unique identifiers (often hashed email addresses or custom headers) within each email to correlate abuse reports with specific users in their system, enabling them to automatically unsubscribe complainers.

December 2024 - Word to the Wise
Expert view

Expert from Spamresource.com shares that the key to automating FBL processing is ensuring you're embedding unique identifiers in your email headers. These can then be extracted from the ARF report to pinpoint the specific recipient and take appropriate action (suppression).

November 2021 - Spamresource.com
Expert view

Expert from Email Geeks explains that most ESPs encode the address in a header or somewhere they can decode. Most FBLs hash the to address and expect the sender to be able to ID the recipient without that.

February 2023 - Email Geeks
Expert view

Expert from Email Geeks answers that most places build their own FBL processing systems.

January 2023 - Email Geeks

What the documentation says
5Technical articles

Email service providers (ESPs) process feedback loop (FBL) emails, which are reports from Internet Service Providers (ISPs) regarding spam complaints. This process involves receiving these reports, often in the Abuse Reporting Format (ARF), parsing them to extract user information, identifying the users who triggered the complaints, and then suppressing them from future mailings. This helps to maintain a healthy sending reputation and prevent deliverability issues caused by high spam complaint rates.

Key findings

  • FBL Reports: ISPs send reports about spam complaints to ESPs through FBLs.
  • ARF Format: FBL reports are often in the Abuse Reporting Format (ARF).
  • User Identification: ESPs identify users who trigger spam complaints from FBL reports.
  • Suppression: Identified users are suppressed from future mailings.
  • Deliverability Impact: High spam complaint rates negatively impact deliverability.

Key considerations

  • FBL Monitoring: Implement a system for monitoring and processing FBLs.
  • ARF Parsing: Develop the ability to parse ARF reports to extract user information.
  • Suppression Lists: Maintain accurate and up-to-date suppression lists based on FBL feedback.
  • Reputation Management: Actively manage FBLs to maintain a healthy sending reputation and ensure deliverability.
Technical article

Documentation from RFC Editor explains that the Abuse Reporting Format (ARF) is a standard format for feedback reports about email abuse. It provides a structured way for ISPs to report spam complaints, which ESPs can then parse to identify and suppress offending users.

September 2021 - RFC Editor
Technical article

Documentation from SparkPost details that FBL implementation involves parsing ARF (Abuse Reporting Format) reports to extract user information. ESPs then use this information to update their suppression lists and prevent further email delivery to those users.

August 2021 - SparkPost
Technical article

Documentation from Validity Knowledge Base explains that FBL processing involves ISPs sending reports about spam complaints. ESPs then use these reports to identify users who triggered the complaints and suppress them from future mailings.

January 2023 - Validity Knowledge Base
Technical article

Documentation from Return Path (now Validity) explains that feedback loops allow email senders to receive reports from ISPs about recipients marking their messages as spam. Processing these reports involves identifying the complaining subscribers and removing them from future mailings.

March 2024 - Return Path
Technical article

Documentation from Google Postmaster Tools explains that high spam complaint rates can negatively impact deliverability. Monitoring and processing FBLs is crucial for maintaining a healthy sending reputation.

August 2023 - Google