Home Feedback Loop Resources

Please Note: M3AAWG is presenting the educational information listed here as a service to the industry because we recognize that feedback loops can be a valuable tool for reducing spam and protecting end-users. However, M3AAWG does not endorse or recommend any particular provider or resource. While our website includes links to materials created by various third-parties, their products are not affiliated with the Messaging, Malware and Mobile Anti-Abuse Working Group and M3AAWG has no control over this third-party content. The links and information are provided here “as is” without any responsibility for the material and solely for the user’s convenience.

What is a Feedback Loop?

The traditional definition of a feedback loop (FBL) is a mechanism by which an Internet Service Provider (ISP) reports user complaints, based on when a user clicks the Spam or Junk button, back to the sender of the message.  ISPs provide this service to senders to help the sender keep their database clean of subscribers who no longer want to receive the sender’s mail and to improve the relevancy of their mail programs.  Not all ISPs provide this service and there are conditions to enrollment as a sender. The diagram below provides a general overview of how these work.

M3AAWG is providing a list of some currently available feedback loops here as an industry service. Feedback loops today are presented in a variety of formats that cue off of different email header components.  In some cases, they also provide the sender with other information in addition to user complaints.

How Feedback Loops Work

Feedback Loop Formats

Traditional (IP-based)

This format, outlined in RFC 6449 , is the standard used by ISPs to report user complaints back to the sender. It is based on the sending IP and reports are sent in the industry standard Abuse Reporting Format (ARF), which provides the sender with the full message and identification of the user who complained. This format allows the sender to identify and remove subscribers who register complaints from their database.


An Aggregate FBL format is an alternative to the Traditional IP-based format and rolls up aggregate counts of complaints by IP, domain, or an identifier determined by the sender.

Providers of an Aggregate FBL format are more sensitive to sharing the Personally Identifiable Information (PII) of their users.  Therefore, this format does not provide the sender with the full message and does not identify the user who complained about the email.  Although user-specific data is not provided, the aggregate statistics provide the sender with valuable information about how their email program is performing.


Like the Traditional FBL format, Domain-based FBL reports are sent in the industry standard Abuse Reporting Format (ARF), which provides the sender with the full message and information on the user who complained about the email received.  What is different is that the Domain-Based FBL format is based on the sending domain. Senders must sign their mail with DKIM (DomainKeys Identified Mail) to participate in the program and enter the sending domain (d= value in DKIM signature) and the selector (the s= value in DKIM signature) from the DKIM signature during the sign-up process.  This format allows senders on shared IP addresses to receive feedback about their specific email program.


Some Currently Available Feedback Loops

Traditional (IP-based) FBLs:

AOL:  https://www.postmaster.aol.com/fbl-request



Cox:  http://fbl.cox.net/


Fastmail:  http://fbl.fastmail.fm/

Italiaonline: http://fbl.italiaonline.it

La Postehttp://fbl.postmaster.laposte.net



Microsoft JMRP (Outlook.com, Hotmail.com):  https://support.msn.com/eform.aspx?productKey=edfsjmrpp&page=support_hom... (Will require account sign-in or creation)


QQ.comhttp://open.mail.qq.com/ (In Chinese)

Rackspace (formerly Mailtrust):  http://fbl.apps.rackspace.com/

Synacor:  http://fbl.synacor.com/

Telenor: http://fbl.online.no/

Terra:  http://fbl.mail.terra.com.br/?lang=en_US.utf8

USA.NET: http://fbl.usa.net/

United Online/Juno/Netzero:  http://www.unitedonline.net/postmaster/whitelisted.html

Zoho.com:  http://fbl.zoho.com/

Yandex:  http://yandexfbl.senderscore.net/

XS4ALL: http://feedbackloop.xs4all.nl/


Aggregated FBLs:



Outlook.com (SNDS)https://postmaster.live.com/snds/addnetwork.aspx

Signal Spamhttps://www.signal-spam.fr/ (Requires paying to join Signal Spam)


Domain-based FBLs:

Yahoo!:  http://feedbackloop.yahoo.net/ (requires DomainKeys or DKIM)

Mail.ru:  http://postmaster.mail.ru/


Additional Resources

ReturnPath's Universal Feedback Loop that manages many of the feedback loops referenced above: https://returnpath.com/universal-feedback-loop

M3AAWG Feedback Reporting Recommendation, February 2014:


If you would like us to consider adding a feedback loop to this list, please use our website Contact Us form to send us a short description of the service and the FBL signup URL.